US 6358892

I'll search for authoritative information on US patent 6358892, including any litigation activity.

Let me look for independent claims and any litigation/docket activity.

Let me try to retrieve the actual claim set and check for any litigation.

US Patent 6,358,892 — Analyst Summary

Important caveat up front: I was able to retrieve the full patent specification from Google Patents (the authoritative source provided) and confirm bibliographic data from a second aggregator (Unified Patents). However, the fetched Google Patents text truncates before the claims section, so I do not have verbatim claim language. The claim descriptions below are reconstructed from the abstract, specification, and closely related family members — treat them as a plain-language characterization, not a quotation.

Bibliographic Data

Discrepancies to flag (not auto-corrected):

• Unified Patents lists the application date as 1998‑01‑26, priority date 1995‑11‑30, and grant date 2002‑03‑18 — each one day earlier than Google Patents. I cannot resolve which is authoritative from the sources retrieved; Google Patents (the supplied full text) states 1998‑01‑27 / 1995‑12‑01 / 2002‑03‑19, and I default to that.
• Google Patents itself labels the priority date "an assumption and not a legal conclusion."

Continuity (from the specification): This application is a division of Ser. No. 08/631,648, filed Apr. 9, 1996, now US 5,716,912, which is a continuation-in-part of Ser. No. 08/566,231, filed Dec. 1, 1995, now US 5,821,205. Related family members include US 5,849,676, US 6,146,431, and EP 0 825 249 B1.

Abstract (as stated)

A succinimide composition is prepared by reacting a mixture of (a) an alkenyl- or alkylsuccinic acid derivative, (b) an unsaturated acidic reagent copolymer, and (c) a polyamine under reactive conditions; then treating the reaction product with a cyclic carbonate, a linear mono- or polycarbonate, or a boron compound. The alkenyl/alkyl substituent of (a) has Mn 1800–3000; the copolymer (b) has Mn 2000–4800 and is a copolymer of an unsaturated acidic reagent and an olefin averaging 14–30 carbons; the polyamine (c) has at least three nitrogens and 4–20 carbons. The mixture contains 1.5–10 equivalents of (a) per equivalent of (b), and 0.4–1.0 moles of polyamine per equivalent of (a) plus (b).

Plain-Language Overview of the Independent Claims

Note: exact claim numbering/wording not retrieved; the following reflects the invention as consistently described across the patent text and family. At minimum there appear to be independent claims to (i) the reaction product/composition, (ii) the post-treated derivatives, and (iii) lubricating-oil, concentrate, and fuel compositions.

1. Composition/reaction-product claim (process-defined product). A succinimide (dispersant) composition made by reacting, under reactive conditions, a mixture of:

   • an alkenyl or alkylsuccinic acid derivative whose alkenyl/alkyl group has a number-average molecular weight (Mn) of 1800–3000 (preferably 2000–2500; polyisobutenyl succinic anhydride — PIBSA — from a thermal process is preferred, making it essentially chlorine-free);
   • an unsaturated acidic reagent copolymer (preferably maleic anhydride/α-olefin) having Mn 2000–4800, where the olefin averages 14–30 carbon atoms (e.g., C14/C16/C18 mixtures); and
   • a polyamine with at least three nitrogen atoms and 4–20 carbons (preferably 6–10 nitrogens; e.g., HPA-X heavy polyamine, TEPA, or DETA/HPA-X blends);

   with the molar charge ratios specified: 1.5–10 equivalents of (a) per equivalent of (b) and 0.4–1.0 moles of polyamine per equivalent of (a)+(b). (The specification notes that below 1.5 equivalents of (a) per mole of (b), gels undesirably form.)

2. Post-treated derivative claim. The above polymer/composition further reacted with a cyclic carbonate (preferably ethylene carbonate), a linear mono- or polycarbonate (or chloroformate), and/or a boron compound (e.g., boric acid), the carbonate reaction occurring at secondary/primary amines of the polyamino moiety. The stated benefits are improved dispersancy, hydrolytic and shear-stability, and fluorocarbon-elastomer seal compatibility.

3. Lubricating oil composition claim. A major amount of an oil of lubricating viscosity plus a minor (effective) amount of the above compound(s) — typically ~1–5 wt% on a dry/actives polymer basis.

4. Concentrate claim. ~20–60 wt% of the compound(s) with ~40–80 wt% compatible liquid diluent (or, per the specification's broader recitation, 10–90 wt% additive in 90–10 wt% diluent).

5. Fuel composition claim. A major amount of gasoline- or diesel-range hydrocarbons plus 10–10,000 ppm (preferably 30–2,000 ppm) of the compound(s).

There are also dependent features described (e.g., W as specified nitrogen-containing groups; Z as a polyalkylene polyamine linking radical with 3–7, more preferably 4–5, nitrogen atoms; R¹ alkyl of 12–28 carbons; Int./Ter. initiator/terminator radicals; formula (I)/(II)/(III) structures).

Litigation / CAFC 2026 Dockets

I found no evidence of any Court of Appeals for the Federal Circuit (or other) 2026 docket activity involving US 6,358,892. Multiple targeted searches (patent number + "CAFC," "docket," "infringement," "Chevron Phillips") returned no litigation hits; results for "6358892" otherwise surfaced unrelated products (e.g., a German OBO ceiling-mount catalog item). I cannot access a live PACER/CAFC docket system through the tools available, so this is a negative search result, not a certification that no docket exists. Practically, the patent being expired since 2015‑12‑01 makes active 2026 infringement/appeal litigation on the '892 patent itself unlikely (though family members or later-generation patents could be at issue).

Confidence & Uncertainties

• High confidence: title, inventors, assignees, application number, subject matter, abstract, and general claim scope.
• Moderate confidence: exact filing/priority/issue dates (two sources differ by one day; I default to the Google Patents text).
• Low confidence / explicitly uncertain: verbatim independent-claim numbering and wording, and the absence of litigation (tools could not query PACER/CAFC directly). I did not locate the US 5,849,676 or US 5,716,912 full claim sets in the retrieved material either, so the independent-claim overview is inferred. If exact claim language is needed for a legal purpose, pull the granted patent's claims directly from USPTO Patent Center or the patent PDF.

I'll search for litigation involving US patent 6358892.

Let me dig deeper into litigation databases and specific case searches.

Summary: No confirmed litigation found for US 6,358,892

Based on my searches (Google Patents, the Unified Patents portal, and general web/court-record searches targeting the exact number "6358892" and "6,358,892"), I was unable to identify any litigation involving US Patent 6,358,892 — no infringement suits, declaratory judgment actions, IPRs/PGRs, or appeals.

What I searched and what I found

• Unified Patents portal (patent page US-6358892-B1): the entry shows bibliographic data only (assignee Chevron Phillips Chemical Co LP; original assignee Chevron Chemical Co LLC; grant 2002-03-18; expiration 2015-11-30) and no litigation section listing any cases. (portal.unifiedpatents.com/patents/patent/US-6358892-B1)
• Google Patents page for US6358892B1: no litigation/litigation-history entries surfaced. (patents.google.com/patent/US6358892)
• General web searches for the patent number combined with "litigation," "lawsuit," "infringement," and "PACER" returned only the patent document itself, unrelated documents that merely cite it as prior art (e.g., a JP national-phase search report, an EP prosecution file), and unrelated dockets unconnected to the '892 patent.

Caveats on confidence

• I do not have live PACER, Docket Alarm, or CourtListener access confirmed for a number-specific hit, and my tool calls were truncated before I could complete additional targeted docket searches. So this is a "not found" result rather than a verified negative.
• The patent's anticipated expiration was 2015-12-01 and it is now marked "Expired – Lifetime." Any litigation would necessarily predate expiry, and older district-court dockets are not always fully indexed in the free sources I could reach.
• Search results can lag real-world filings; if absolute completeness is required, a paid docket search (LexisNexis CourtLink, Docket Navigator, or PACER's Patent Litigation Docket Report) keyed to "6,358,892" should be run.

Bottom line

No known litigation involving US 6,358,892 could be identified. I am not able to state affirmatively that none exists — only that my searches did not surface any case (plaintiff, defendant, jurisdiction, case number, filing date, or outcome) tied to this specific patent. I have not fabricated any case details, because none were found.

I'll verify the structured data against live sources before drafting.

Proceedings overview

Total AIA trial proceedings on US 6,358,892: zero. The USPTO Open Data Portal returns no IPR, PGR, or CBM proceedings, and my independent web searches (Google Patents, Unified Patents' patent portal, PTAB/docket aggregator results, and general IPR-news queries) surfaced no petition, institution decision, Final Written Decision, or Federal Circuit appeal naming this patent. The breakdown is therefore 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials — and because nothing was ever filed, no claims have been canceled, narrowed, or confirmed. Defensive posture: the patent has never been tested at the PTAB, but that is irrelevant in practice — US 6,358,892 expired on 2015-12-01 and is now more than a decade past its term, so 35 U.S.C. § 286's six-year damages lookback bars any meaningful recovery on any complaint filed today. The absence of PTAB activity is explained by expiry and the commercial history of the family, not by unusual patent strength.

There are no per-proceeding sections to write. Instead, here is what the zero-count record actually means.

No proceeding to report — {N/A} v. {N/A}

• Type: Not applicable. No Inter Partes Review, Post-Grant Review, or Covered Business Method review has ever been instituted against US 6,358,892 on the record available to me.
• Filed: 2026-09-30. Source of record: the structured "PTAB proceedings on file" block (USPTO ODP ingest), cross-checked against Google Patents US6358892B1 and Unified Patents' US-6358892-B1 portal page, neither of which lists any PTAB trial.
• Status: No proceedings on file (ODP), confirmed by search. Note the Google Patents legal-status field for this patent reads "Expired - Lifetime," with "Anticipated expiration 2015-12-01."
• Judge panel: None — no panel has ever been assigned.
• Petition grounds: None. No § 102 / § 103 / § 112 ground has ever been presented to the Board on this patent, so no § 315(e)(2) estoppel exists against anyone.
• Institution decision: None.
• Final Written Decision: None. I therefore cannot and do not represent that any claim of this patent was canceled, confirmed, or construed by the PTAB.
• Settlement / termination: None.
• Appeal: None found at the Federal Circuit. No CAFC docket number exists to cite; CourtListener and the CAFC docket search returned nothing tying a PTAB appeal to this patent.
• Defensive value: The practical defense here is expiry, not invalidity. US 6,358,892 claims priority to 1995-12-01 and, as a divisional of the 08/566,231 chain (now US 5,821,205, via 08/631,648, now US 5,716,912), its 20-year term ran out on 2015-12-01. A complaint filed on or after 2021-12-01 cannot reach any recoverable infringement under § 286, and one filed today (2026-09-30) has no damages window at all. Do not spend IPR money; check the demand letter for a live pre-2015 damages theory instead.

One accuracy caution: I found no evidence of a PTAB proceeding, but I also cannot prove a universal negative from web searches alone. Before you rely on this, pull the patent's prosecution/trial history directly from USPTO Patent Center and the Board's PTAB E2E proceeding search, and run a district-court docket check (PACER or Docket Alarm) for any assertion of the '892. A pre-AIA ex parte or inter partes reexamination would not appear in the AIA-trial list either; none surfaced in my searches, but the ex parte route is anonymized by design and is best confirmed through Patent Center's transaction history.

Strategic summary

Claim status. Because there is no AIA trial record, no claim of 6,358,892 has been canceled, amended, or held patentable by the PTAB — the claims stand exactly as they issued on 2002-03-19, subject only to whatever occurred in original prosecution. I do not have the issued claim set in front of me (the text available to me is cut off before the claims), so I cannot state the total number of claims or list surviving claims, and I will not guess at claim numbers. The operative fact is not the claim count but the calendar: the patent's anticipated expiration is 2015-12-01.

Estoppel landscape. With zero proceedings, § 315(e)(2) estoppel is a non-factor — no petitioner, no privy, no ground was ever "raised or reasonably could have been raised" before the Board. If you are a defendant today, the entire prior-art universe remains available to you in district court under §§ 102/103 and § 282, unburdened by any IPR estoppel. Conversely, if you elect to file your own IPR, you would be building estoppel against yourself for nothing, given the expiry and the § 286 problem discussed above.

Pattern signals. No serial filer, no defensive aggregator, no petitioner at all. Unified Patents maintains a patent page for the '892 (a monitoring artifact, not a challenge — Unified's portal indexes patents whether or not it has ever filed against them; its presence is not evidence of a Unified IPR). Chevron Phillips Chemical Co LP is the current assignee and Chevron Chemical Co LLC the original assignee; I found no evidence that either pursued PTAB appeals on this patent, because there were no PTAB outcomes to appeal. On the family side, US 5,821,205 and US 5,716,912 share the same specification lineage and the same claimed expiry chain; my searches did not surface AIA trials on those siblings either, but the canonical ODP block in this prompt covers only the '892, so treat the siblings as unverified rather than confirmed clean. The stale-search noise you may encounter (e.g., hits on US 5,825,898, US 6,483,923, US 6,377,637 in IPR2015-01391/-01392/-01396) concerns a different patent family and a different petitioner campaign — do not import those outcomes onto this patent.

Why zero is not a strength signal here. Roughly 80% of IPRs target patents already asserted in district court. This patent's enforceable life ended in 2015, and I found no aggressive assertion campaign that would have drawn a petition. A quiet PTAB record on an expired, largely unasserted 1995-priority lubricant-additive patent is unremarkable — it does not mean the claims would have survived review.

Recommended next steps

1. Lead with expiry and § 286, not invalidity. If a demand letter cites US 6,358,892, the dispositive response is that the patent expired 2015-12-01 (per Google Patents: "Anticipated expiration 2015-12-01," legal status "Expired - Lifetime") and that 35 U.S.C. § 286 forecloses damages for any infringement committed more than six years before suit. No new action filed as of today has a live damages window. There is no FWD to link or quote, because none exists.
2. Confirm the negative on the official systems before filing anything. Query PTAB E2E for proceedings by patent number, and check the ODP at data.uspto.gov plus Patent Center's transaction history for any ex parte reexamination or certificate of correction that the AIA-trial list would not capture. Document the null result in your file.
3. Docket-check for a lingering case. If a co-defendant or an earlier suit is still open, an expired patent can still support past damages for pre-2015 conduct within the § 286 window of that suit's filing date. Pull the docket and the accused-product date ranges.
4. Verify the family separately. US 5,821,205 and US 5,716,912 sit on the same priority chain and share the same 2015-12-01 term endpoint; run the same PTAB E2E and Patent Center checks on each rather than assuming this patent's clean record carries over.
5. Do not file an IPR. With the patent expired and untested, an IPR would buy you nothing defensively while creating § 315(e)(2) estoppel against your own district-court invalidity case on grounds you could otherwise raise freely.

I'll research the assignment record for US 6358892 before building the chain.

US 6358892 — Assignment & Ownership Reconstruction

Patent: US 6,358,892 B1 — "Polyalkylene succinimides and post-treated derivatives thereof"
App. No.: 09/176,278 (filed 1998-01-27); divisional of 08/631,648 (filed 1996-04-09, now US 5,716,912), itself a CIP of 08/566,231 (filed 1995-12-01, now US 5,821,205)
Granted: 2002-03-19 · Priority: 1995-12-01 · Expired: 2015-12-01

Verification limitation up front: the USPTO Assignment Center (https://assignmentcenter.uspto.gov/, mirrored at https://assignment.uspto.gov/patent/index.html) is an interactive, session-based search that does not expose per-patent reel/frame records to the sources I could reach. Google Patents' legal-events panel for this patent likewise shows only the derived labels "Original Assignee: Chevron Chemical Co LLC" and "Current Assignee: Chevron Phillips Chemical Co LP," with Google's own caveat that "the listed assignees may be inaccurate." I could not retrieve a single confirmed reel/frame entry for US 6358892. Everything below is flagged accordingly; I have not invented reel/frame numbers.

---

Inventors

• Both inventors are career Chevron additives researchers; the invention is squarely lubricant-additive chemistry (polyalkylene succinimide dispersants, fluorocarbon-elastomer compatibility, soot dispersancy), i.e. Oronite-class subject matter.
• Departure pattern: unclear / no evidence. I found no record of either inventor leaving the Chevron organization within 12 months of filing, nor any later inventor-side assignment to an unrelated party. There is no evidence of the "inventors bail out, then portfolio fire-sale" precursor pattern. This is a not-observed call, not a negative finding.
• One relevant data point did surface — a recorded assignment by James J. Harrison to CHEVRON ORONITE COMPANY LLC, recorded 2001-11-09 at Reel 012695 / Frame 0053–0060, cover-sheet dockets T-5565 and T-5575 (source: legacy-assignments.uspto.gov/assignments/assignment-pat-012695-0053.pdf). This is an intra-Chevron confirmatory assignment, not a third-party transfer. I cannot confirm that docket T-5565 or T-5575 corresponds to application 09/176,278, so it is offered only as contextual evidence that Chevron Oronite took inventor assignments in this technology area in late 2001.

---

Original assignee

Chevron Chemical Company LLC (named on the issued patent per Google Patents; the application was filed 1998-01-27, after Chevron Chemical Company was reorganized as a Delaware LLC).

• Primary line of business: petrochemicals and fuel/lubricant additives. Chevron Chemical Company was the Chevron Corporation subsidiary housing both the Oronite additives business and the olefins/polyolefins petrochemical business.
• Product embodying the claims: Yes, in the ordinary operating-company sense — Chevron Oronite is the world's largest merchant supplier of lubricant and fuel additives, and polyisobutenyl succinimide dispersants of this class are (and were) commercial products. However, the patent has expired (2015-12-01) and I found no product literature tying this specific claim set to a branded commercial product.
• Current status of the original assignee entity: not operating under that name. Chevron Chemical Company LLC was split in the 1999–2001 restructuring:
  • Oronite (fuel and lubricant additives) → Chevron Oronite Company LLC, still an operating Chevron subsidiary today.
  • Petrochemicals → contributed to the Chevron/Phillips joint venture Chevron Phillips Chemical Company LLC (now LP), formed under a Contribution Agreement dated 2000-05-23 (Chevron Corporation Form 8-K, event date 2000-05-23, filed 2000-06-02; https://chevroncorp.gcs-web.com/static-files/4a3db3d0-e3ea-483b-bb65-7b2df188f6ba).

Material cross-check — this is the key evidentiary point on ownership. The Chevron/Phillips Contribution Agreement defines "C Chem Patent Rights" to be contributed to the JV, but expressly carves out patents whose claims "cover Oronite technology for fuel and lubricant additives or additive precursors and their manufacture and blending and products, packages, and formulations containing such additives." US 6,358,892 claims lubricating-oil and fuel dispersants — squarely inside the Oronite carve-out. The technology therefore most plausibly remained with the Chevron side (Chevron Chemical Company LLC → Chevron Oronite Company LLC), which is inconsistent with the "Current Assignee: Chevron Phillips Chemical Co LP" label Google Patents prints — and Google's own disclaimer ("assignees may be inaccurate") covers exactly this kind of derived-field error.

---

Assignment timeline

Plain finding: no assignment reel/frame record for US 6358892 could be verified through the sources available to me. I am not going to manufacture reel/frame entries to fill the gap.

What can be stated from the record I could actually reach:

• Pre-issue — assignee of record: Chevron Chemical Company LLC. The patent issued 2002-03-19 to a Chevron entity; no third-party assignment appears in any source I could retrieve. Reel/frame: not retrieved.
• 2001-11-09 (recorded) — Reel 012695 / Frame 0053 — not confirmed to cover this patent
  • Conveyance: Assignment (inventor-to-company, confirmatory)
  • Assignor: James J. Harrison (inventor)
  • Assignee: Chevron Oronite Company LLC, San Ramon, California
  • Correspondent: not shown in the retrieved cover-sheet excerpt
  • Context: internal reorg — Chevron's additives business being papered into the Oronite entity; a same-owner reorganization, not an arm's-length sale
  • Caveat: dockets T-5565 / T-5575; correspondence to app. 09/176,278 unverified.
• Post-2001 → 2015: No assignment, license, security interest, or release recorded against this patent that I could locate. The patent lapsed at end of term on 2015-12-01 with no assertion activity found.

Correspondent-of-record capture: not obtainable for this chain from the reachable sources. I can therefore make no recurrence finding under the repeat-correspondent signal — which per your rules means the signal stays unclear, not absent.

---

Timeline diagram

Only independently verifiable events are plotted. Post-issuance ownership records could not be confirmed and are deliberately excluded rather than shown speculatively.

timeline
    title Ownership of US 6358892
    1995 : Priority application filed
    1996 : Continuation in part filed
    1998 : Divisional application filed
    2002 : Patent issued
         : Assignee of record Chevron Chemical
    2015 : Patent term expired

---

NPE / troll-pattern signals

---

Verdict

Insufficient data — no assignment records for US 6358892 could be verified, and only the original/inventor-side assignment history is documented.

Justification: I could not retrieve a single confirmed reel/frame entry from the Assignment Center or any mirror for this patent, so the chain cannot be reconstructed to the standard your rubric requires — no correspondent, no execution dates, no conveyances. The evidence I could reach points the other way from an NPE reading: the 2000-05-23 Chevron/Phillips Contribution Agreement (Chevron 8-K, filed 2000-06-02) expressly carves Oronite fuel- and lubricant-additive patents out of the JV contribution, which places this dispersant patent on the Chevron Oronite side of an intra-corporate restructuring, and Unified Patents' portal shows zero litigation and zero IPR activity before the patent expired on 2015-12-01. Read substantively this is a plain operating-company chain with no NPE signal, but because the concrete assignment records are unverified, "Insufficient data" is the honest call rather than a clean "defensive / non-asserting."

Verify directly: https://assignmentcenter.uspto.gov/ (search patent number 6358892) — pull the reel/frame list and the correspondent of record, which are the two fields I could not capture.

I'll research the prior art citations for US 6,358,892. Let me search multiple sources.

Let me get the specific front-page citations for US 6,358,892 from the patent databases.

Let me retrieve the exact front-page citations list for US 6,358,892 from FreePatentsOnline.

Prior-Art Analysis — US 6,358,892 B1

A. Patent identification (literal)

Scope to be anticipated. US 6,358,892's abstract and disclosure define a succinimide composition prepared by reacting a mixture of:

• (a) an alkenyl/alkylsuccinic acid derivative whose alkenyl/alkyl substituent has Mn 1800–3000;
• (b) an unsaturated acidic reagent copolymer (unsat. acidic reagent + olefin averaging 14–30 carbons), the copolymer having Mn 2000–4800;
• (c) a polyamine having ≥3 N atoms and 4–20 C atoms;
• (d) charge ratios of 1.5–10 equiv (a) per equiv (b) and 0.4–1.0 mol (c) per equiv (a)+(b);

plus (e) optional post-treatment with a cyclic carbonate, linear mono-/polycarbonate, or boron compound, and (f) lubricating-oil, concentrate and fuel compositions.

⚠️ Flag (contradiction avoidance): the earlier search output returned a full claim set on the Justia page for US 6,015,776 (claim 1 reciting "Mn of from 140 to 3000" and "olefin having a Mn of at least 1000"). Those are NOT the claims of US 6,358,892 — 6,015,776 is a different sibling in the same Chevron family. I do not treat that claim text as belonging to '892.

---

B. Front-page cited U.S. patent documents ("References Cited")

The following is the reference list appearing on the face of US 6,358,892 (as indexed by Justia's patents.justia.com/patent/6358892):

Per-reference description and § 102 potential

1. US 3,172,892 — LeSuer et al., Mar. 9, 1965. Chlorination-process preparation of alkenylsuccinic anhydride from chlorinated polyolefin + maleic anhydride, and its reaction with polyamines to give alkenyl succinimide dispersants. § 102 potential: could anticipate claims drawn solely to reacting an alkenylsuccinic acid derivative (a) with a polyamine (c) — but it discloses no unsaturated-acidic-reagent copolymer (b), no olefin of 14–30 C, no copolymer Mn 2000–4800, and no ratios of (d). Not anticipatory of the composite claims.

2. US 3,219,666 — Norman et al., Nov. 23, 1965. Derivatives of polyalkenyl succinic acids/anhydrides with nitrogen compounds (incl. polyamines) as lubricant dispersants; preferred polyalkenyl Mn 750–5,000. § 102: same gap as (1) — anticipates at most a two-component PIBSA/polyamine sub-combination.

3. US 3,361,673 — Stuart et al., Jan. 2, 1968. The thermal (ene) reaction of a polyolefin with maleic anhydride (the source of the "thermal PIBSA" used in the '892 examples). § 102: potentially anticipates only the process of making reactant (a); silent on (b)–(d).

4. US 3,381,022 — LeSuer, Apr. 16, 1968. Ester derivatives of polyolefin-substituted succinic acids (acidic esters, diesters, metal-salt esters). § 102: relevant only to ester-type claims; the '892 claims are imide/polyamine-based, so no anticipation.

5. US 3,455,827 — Mehmedbasich, Jul. 15, 1969. ⚠️ Description not verified in this session — cited for succinimide/dispersant lubricant-additive art. Treat as general background; no specific anticipation attributed.

6. US 3,912,764 — Palmer, Jr., Oct. 14, 1975. Combined thermal + chlorination process for making alkenylsuccinic anhydride. § 102: process-only art for reactant (a).

7. US 4,234,435 — Meinhardt et al., Nov. 18, 1980. "Multiply-adducted" polyisobutenyl succinic acylating agents (≥1.3 succinic groups per polyalkene equivalent; Mn 1500–3200; Mw/Mn 1.5–4) reacted with polyamines; also teaches VI-improving dispersants. § 102: the '892 claims require a succinic ratio of only 1:1–1.5 (pref. 1:1–1.2), so '435's high-succination species do not meet the claim limitations; it also lacks the copolymer (b).

8. US 4,612,132 — Wollenberg et al., Sep. 16, 1986. Cyclic/linear carbonate or chloroformate modification of alkenyl/alkyl succinimides via the polyamine nitrogens (improved dispersancy). § 102: anticipates the post-treatment feature (e) in isolation, and is the express procedural source cited in the '892 specification for the ethylene-carbonate step; does not disclose the (a)+(b)+(c) polymer backbone.

9. US 4,747,965 — Wollenberg et al., May 31, 1988. As '132 but derived from succinimides having >1.0 succinic groups per long-chain alkenyl substituent. § 102: same as (8) for feature (e).

10. US 5,112,507 — Harrison, May 12, 1992. ⭐ Most relevant. Polymeric "ladder-type" polysuccinimides made by reacting a maleic anhydride–olefin copolymer with a polyamine (long-chain alkyl/alkenyl side chains, generally ≥30 C, preferably ≥50 C); expressly taught to be post-treatable with cyclic carbonates, linear mono-/polycarbonates, and boron compounds (boric acid), and to have improved hydrolytic and shear-stress stability. § 102 potential: this is the closest single reference to the (b)+(c)+(e) architecture. It does not disclose the separate alkenyl/alkylsuccinic acid derivative (a) with Mn 1800–3000, the olefin of 14–30 C, the copolymer Mn 2000–4800, or the charge ratios (d). Anticipation would require reading the record to find those limitations — likely a § 103 reference rather than a § 102 reference.

11. US 5,241,003 — Degonia et al., Aug. 31, 1993. Post-treatment compendium (columns 27–29 of which are expressly incorporated by the '892 specification as the catalogue of post-treatments). § 102: anticipates only the post-treatment feature; no backbone disclosure.

12. US 5,266,186 — Kaplan, Nov. 30, 1993. ⭐ Most relevant. Discussed in the '892 background: Example 2 prepares a dispersant by reacting certain polyisobutenyl-succinic anhydride adducts with ethylenediamine, followed by reaction with a maleic anhydride/α-olefin copolymer (iron-sulfide dispersant for refinery streams). § 102 potential: this is the only cited patent that discloses the same reaction concept — PIBSA + polyamine + MA/olefin copolymer. But it (i) uses ethylenediamine (only 2 N, below the claimed ≥3 N), (ii) does not disclose Mn 1800–3000 for (a), (iii) does not disclose olefin 14–30 C or copolymer Mn 2000–4800, and (iv) does not disclose the (d) ratios. It is best characterized as the closest conceptual prior art and a strong § 103 candidate, not a clean § 102 anticipation.

13. US 5,286,799 — Harrison et al., Feb. 15, 1994. Free-radical process for preparing alkenyl succinic anhydrides (cited in the '892 background). § 102: process art for reactant (a) only.

14. US 5,319,030 — Harrison et al., Jun. 7, 1994. Free-radical PIBSA process (co-cited with '799). § 102: as (13).

15. US 5,334,321 — Harrison et al., Aug. 2, 1994. Cyclic-carbonate post-treated alkenyl/alkyl succinimides with improved fluorocarbon-elastomer compatibility; also the source of the "succinic ratio" calculation the '892 specification incorporates. § 102: anticipates the post-treatment (e) and, arguably, the end-use compositions; not the three-component backbone.

16. US 5,356,522 — Lal et al., Oct. 18, 1994. ⚠️ Description not verified in this session. Cited apparently for succinimide/dispersant art; no specific anticipation attributed.

17. US 5,356,552 — Harrison et al., Oct. 18, 1994. Cyclic-carbonate post-treated succinimides prepared from substituted succinic anhydride + a polyamine having ≥4 N per mole. § 102: as (15).

18. US 5,716,912 — Harrison et al., Feb. 10, 1998. The direct parent (the application of which '892 is a divisional). Discloses a polysuccinimide from alkenyl/alkylsuccinic acid derivative (Mn 1800–3000) + unsaturated acidic reagent copolymer (olefin of 14–30 C; Mn 2,000–4,800) + polyamine, with carbonate/borate post-treatment. § 102/§ 102(e)/double-patenting potential: this reference maps almost 1:1 onto the '892 disclosure. Because it is the same family/same inventive entity, expect it to have been handled by terminal disclaimer / obviousness-type double patenting rather than substantive § 102 rejection.

19. US 5,821,205 — Harrison et al., Oct. 13, 1998. The grandparent (08/566,231). Same reaction concept; olefin 12–18 C, polyamine ≥6 N. § 102 potential: same family; nearly co-extensive disclosure.

20. US 5,849,676 — Harrison et al., Dec. 15, 1998. "Post-treated derivatives of polyalkylene succinimides." § 102 potential: family member; discloses the post-treated polymer architecture.

21. US 5,851,965 — Harrison et al., Dec. 22, 1998. Family member (succinimide dispersant compositions). § 102 potential: family art.

22. US 5,853,434 — Harrison et al., Dec. 29, 1998. Family member directed to fuel compositions containing these dispersants. § 102 potential: anticipates at most the fuel-composition claims (f) if all structural limitations are met.

23. US 5,872,083 — Harrison et al., Feb. 16, 1999. "Post-treated derivatives of polyalkylene succinimides." § 102 potential: family member; post-treatment architecture.

---

C. Cited foreign patent documents

---

D. Cited non-patent literature

1. E. S. Forbes and E. L. Neustadter, "The Mechanism of Action of Polyisobutenyl Succinimide Lubricating Oil Additives," Tribology, Vol. 5, No. 2, pp. 72–77 (Apr. 1972). Discusses the effect of polyisobutenyl Mn on detergency; concludes maximum detergency at ~1300 Mn — contrary to the '892 preference for Mn 1800–3000. § 102: a printed publication, but it discloses no three-component polymer; not anticipatory.
2. S. T. Roby, R. E. Kornbrekke and J. A. Supp, "Deposit Formulation in Gasoline Engines, Part 2, Dispersant Effects on Sequence VE Deposits," J. Soc. Tribologists and Lubrication Engineers, Vol. 50, No. 12, pp. 989–995 (Dec. 1994). Teaches that, at equal N, 2000-dalton side-chain succinimides outperform 1000-dalton ones. § 102: supports the Mn rationale; no compositional disclosure of the claimed polymer.

---

E. Ranking — most relevant prior art for US 6,358,892

1. US 5,716,912 (parent) / US 5,821,205 (grandparent) and family (5,849,676; 5,851,965; 5,853,434; 5,872,083) — near-identical disclosure; handled as double-patenting/§ 102(e)/terminal-disclaimer art, not substantive novelty art.
2. US 5,112,507 (Harrison) — closest backbone teaching (MA–olefin copolymer + polyamine, carbonate/boron post-treatment, hydrolytic/shear stability).
3. US 5,266,186 (Kaplan) — closest reaction-concept teaching (PIBSA + diamine + MA/α-olefin copolymer), but fails the ≥3 N and Mn/olefin/ratio limitations.
4. EP 0 682 102 A2 — closest foreign teaching of the (a)+(b)+(c) reaction, subject to the numeric limitations; date on the printed list is erroneous (Nov. 1995, not 1965).
5. US 4,612,132 / 4,747,965 / 5,334,321 / 5,356,552 / 5,241,003 — establish the post-treatment (e) feature; would anticipate only if all other limitations were present in the record.
6. Remaining references (3,172,892; 3,219,666; 3,361,673; 3,381,022; 3,455,827; 3,912,764; 4,234,435; 5,286,799; 5,319,030; 5,356,522 and the EP/GB documents) — background/process art for the individual reactants; individually non-anticipatory.

---

F. Bottom line and caveats

• No single cited reference appears to disclose every limitation of the US 6,358,892 claims (particularly the concurrence of: substituent Mn 1800–3000; olefin of 14–30 C; copolymer Mn 2000–4800; polyamine ≥3 N/4–20 C; and the two charge-ratio ranges). The strongest candidates are the applicant's own parent/grandparent family (double-patenting/§ 102(e)) and the EP 0 682 102 A2 / US 5,266,186 / US 5,112,507 trio as § 103-type art.
• I was unable to verify the exact wording and numbering of the claims of US 6,358,892 in this session (the supplied full text was truncated before the claims). Consequently, the claim numbers cited above are keyed to the abstract/description limitations, not to verbatim claim language. If claim-by-claim § 102 mapping is required, the issued claims (and any reexamination certificates) should be obtained from USPTO PatentCenter.
• Descriptions for US 3,455,827 (Mehmedbasich) and US 5,356,522 (Lal et al.) are marked as unverified — I do not have high-confidence knowledge of their exact disclosures, and I have not fabricated them.
• Date anomaly flagged, not auto-corrected: the front-page list renders EP 0 682 102 as "November 1965"; the reference is a 1995 publication. Likewise, the claim text returned by one search engine belongs to sibling US 6,015,776, not to '892.

Sources consulted: Justia patent page for US 6,358,892 (front-page "Referenced Cited" list); Google Patents US6358892B1; Unified Patents portal US-6358892-B1; the '892 specification text; and sibling-family pages (US 5,821,205, US 5,849,676, US 6,015,776) used only for background on shared terminology.

I'll ground the analysis by pulling details on the key prior-art references cited in this patent's specification.

Obviousness Analysis — US 6,358,892 B1 under 35 U.S.C. § 103

0. Scope, assumptions, and caveats

What I'm analyzing. The independent claims of US 6,358,892 as characterized earlier in this analysis: (i) a succinimide composition/reaction product of (a) an alkenyl- or alkylsuccinic acid derivative (Mn 1800–3000), (b) an unsaturated acidic reagent copolymer (Mn 2000–4800; olefin averaging C14–C30), and (c) a polyamine (≥3 N, C4–C20), at 1.5–10 eq (a) per eq (b) and 0.4–1.0 mol polyamine per eq (a)+(b); (ii) post-treated derivatives thereof (cyclic carbonate / linear mono- or polycarbonate / boron compound); and (iii) lubricating-oil, concentrate, and fuel compositions.

Caveat carried forward. The Google Patents fetch of US 6,358,892 truncates before the claims. I do not have verbatim claim language. The element map below is reconstructed from the abstract and specification and should be verified against the granted claims before any legal use.

Governing law. Priority is 1995-12-01, so the pre-AIA (Graham/KSR) framework applies. Obviousness is judged from the perspective of a PHOSITA at the critical date, with the patent claim presumed valid (clear-and-convincing burden — Microsoft v. i4i, 564 U.S. 91 (2011)).

Critical point on what counts as prior art in this record. The patent's own "Prior Art" discussion is the authoritative reference inventory supplied on this page. But the record also contains several documents that are NOT prior art and must be excluded from any §103 combination:

• CA 2,212,495 C / EP 0 831 104 A2 ("Novel dispersant terpolymers") / US 5,859,965 / US 6,146,431 / US 5,849,676 / EP 0 826 349 (EP 102?) — these are Chevron/Same-inventor family members sharing the disclosure language verbatim (e.g., "We use 1-olefins from C10 to C30… Mixtures of olefins, e.g., C14, C16, and C18, are especially desirable"). They cannot be combined against the claims.
• DE 697 23373 T2 and DE 696 34332 T2 are German translations of the '892 family background text — not prior art.
• EP 0 776 963 A1 (published 1997-06-04, with the "ANALYTICAL DATA FOR POLYISOBUTENYLSUCCINIMIDE-MALEIC ANHYDRIDE C14-18 OLEFIN COPOLYMER" table) is the same-family publication.

Flagging this explicitly, because a careless searcher could pick one of these up as an "anticipatory" reference.

---

1. Level of ordinary skill

Given the 1995 date and the technology, a PHOSITA is a chemist or chemical engineer with a B.S. in chemistry/chemical engineering and 2–5 years of experience formulating lubricant dispersants, or an M.S./Ph.D. with less experience — someone fully conversant with succinimide dispersant chemistry, PIBSA manufacture (thermal vs. chlorination routes), polyamine selection, and ASTM performance tests (TBN, SAP, TAN, Sequence VE, Panel Coker).

---

2. Prior-art reference inventory (drawn from the patent's own Prior Art section)

---

3. Element-by-element map of the primary independent claim

---

4. The obviousness combinations

Combination 1 — EP 682 102 A2 alone, or in view of US 4,234,435

Primary: EP 0 682 102 A2. Secondary: US 4,234,435.

EP 682 102 A2 discloses the reaction of the same three reactants to make a dispersant/VI improver for lubricating oils. The applicant concedes this in the Background: "EP 0 682 102 A2 discloses a process which comprises reacting: a copolymer of an olefin and maleic anhydride, an acyclic hydrocarbyl-substituted succinic acylating agent, and an alkylene polyamine. These products are useful… as dispersants having viscosity index improver properties."

The only elements not literally present are the Mn windows and the two charge ratios. For Mn, '435 expressly teaches 1500–3200 and, for polybutenes, 1700–2400 — squarely overlapping the claimed 1800–3000/2000–2500. Under In re Peterson, 315 F.2d 571 (CCPA 1963), In re Woodruff, 919 F.2d 1575 (Fed. Cir. 1990), and In re Geisler, 116 F.3d 1465 (Fed. Cir. 1997), a claimed range overlapping or abutting a prior-art range is prima facie obvious absent criticality.

Motivation: both references are in the identical field (crankcase lubricant dispersants), address the identical problem (dispersancy with VI credit), and '435 expressly teaches the very benefit ("impart significant fluidity modifying properties… sufficient to permit elimination of all or a significant amount of viscosity index improver") that EP 682 102 A2 also claims. There is a finite, predictable number of known polyisobutene molecular weights; selecting 1800–3000 is KSR-style "obvious to try."

Expectation of success: high — the chemistry is a simple amidation/imidization of anhydrides with polyamine, and both references report operative products.

Combination 2 — EP 682 102 A2 + US 5,112,507 (+ US 4,234,435)

Primary: EP 0 682 102 A2. Secondaries: US 5,112,507; US 4,234,435.

US 5,112,507 teaches a polymeric succinimide built from maleic anhydride–olefin copolymers and polyamines, described as possessing "improved hydrolytic stability and shear stress stability." The '892 patent's stated objects are "improved stability … particularly hydrolytic stability and shear stress stability." A reference that expressly solves the same problem the applicant identifies is a fortiori combinable (In re Kahn, 441 F.3d 977 (Fed. Cir. 2006); MPEP 2143). The '507 ladder architecture and EP 682 102 A2's ternary reaction are near-identical chemistries, so the combination is a predictable substitution of known elements (KSR Int'l v. Teleflex, 550 U.S. 398 (2007)).

This combination also disposes of the copolymer-Mn limitation. The claimed Mn 2000–4800 is the kind of "result-effective variable" whose optimization is routine (In re Boesch, 617 F.2d 272 (CCPA 1980); In re Antonie, 559 F.2d 618 (CCPA 1977)). Critically, the '892 specification states the direction and reason for the optimization: low-MW copolymers (2000–5500) are preferred because "higher molecular weight copolymers (greater than 10,000 for example) can sometimes produce polymers that contain gels." A predictable, disclosed design rationale is not a patentable discovery.

Combination 3 — Any of the above + US 5,334,321 (or US 5,356,552) and/or US 4,612,132 → post-treated derivative claims

Primary: EP 682 102 A2 (+ '435, '507). Secondary: US 5,334,321 / 5,356,552; US 4,612,132.

The post-treatment claims require reacting the succinimide with a cyclic carbonate (pref. ethylene carbonate), a linear mono-/polycarbonate, or a boron compound.

• US 4,612,132 teaches exactly this post-treatment (cyclic/linear carbonate or chloroformate) and the resulting improvement in dispersancy/detergency.
• US 5,334,321 / 5,356,552 teach the same carbonate post-treatment applied to a PIBSA from polyolefin Mn 2000–2700 reacted with a polyamine having >4 N, expressly to achieve fluorocarbon elastomer seal compatibility. The '892 patent's own Background recites this verbatim.

Motivation is unusually strong because the '892 patent frames its entire invention around the fluorocarbon-elastomer problem: "a drawback of succinimide dispersants is that they have generally been found to reduce the life of fluorocarbon elastomers. In general, for a given succinimide dispersant, a higher nitrogen content gives better dispersancy but poorer fluorocarbon elastomer compatibility." The '321 patent addresses that precise trade-off. When the prior art recognizes and solves the very problem the applicant set out to solve, the motivation requirement is satisfied.

Note on claim structure: if the unpost-treated independent claim does not require carbonate treatment, then the fluorocarbon-elastomer advantage relied on for patentability resides only in the post-treated claims — weakening any nexus argument for the base claim.

Combination 4 — US 5,112,507 as primary + US 5,334,321 + US 4,234,435

Even if one rejects EP 682 102 A2 as the starting point, '507 alone teaches a succinimide from MA–olefin copolymer + polyamine with improved hydrolytic/shear stability. Adding '321 supplies the Mn 2000–2700 window, the >4 N polyamine, the carbonate post-treatment, and the elastomer-compatibility rationale; adding '435 supplies the high-Mn / VI-credit teaching. The motivation is the same as in Combinations 1–3.

Combination 5 — US 5,266,186 Ex. 2 + US 4,234,435 + US 4,612,132

The '892 Background concedes that "Example 2 of U.S. Pat. No. 5,266,186 discloses the preparation of dispersants by reacting certain polyisobutenyl-succinic anhydride adducts … with ethylenediamine, followed by reaction with a maleic anhydride/α-olefin copolymer." This supplies the ternary reactant set and a polyamine-first order of addition (compare the '892 spec: "we have generally found it convenient to first add the alkenyl or alkylsuccinic acid derivative and the unsaturated acidic reagent copolymer together and then add the polyamine" — a mere order-of-addition difference). Motivation is weaker than Combinations 1–4 because '186 is directed to refinery iron-sulfide dispersancy, not crankcase lubricants (a different problem), though the chemistry and the "field of endeavor" remain close enough that a PHOSITA would still consult it. This combination is best used as a cumulative, not standalone, ground.

Combinations 6 — The composition claims (lube oil, concentrate, fuel)

These are conventional formulation claims and fall with the underlying compound claims:

• Lubricating oil (~1–5 wt% actives): taught by '321/'552 ("usually present in from about 1 to about 5 percent by weight (on a dry polymer basis)") and by '435 (lubricating composition claims).
• Concentrate (20–60 wt% / 40–80 wt% diluent; spec. also 10–90/90–10): '321 claims "a lubricating oil concentrate comprising from about 90 to about 10 weight percent of an oil of lubricating viscosity and from about 10 to about 90 weight percent on a dry polymer basis."
• Fuel (10–10,000 ppm; pref. 30–2,000 ppm): EP 0 688 339 B1 (the '552/'321 sibling) states: "the range of concentration of the additive in the base fuel is 10 to 10,000 weight parts per million, preferably from 30 to 2,000 weight parts per million."

These are numeric ranges carried over essentially verbatim from the prior art — textbook overlapping-range obviousness.

---

5. Consolidated motivation-to-combine

---

6. Two secondary points worth noting

(a) The Int./Ter. radicals carry no patentable weight. The claim language recites "Int. is an initiating radical; Ter. is a terminating group," and the specification states they "are carried over into the present composition from the maleic anhydride reactant and are present in the copolymer reactants as a result of the free radical initiator used to prepare the copolymer." EP 682 102 A2's Example 1 polymerizes in xylenes with tert-butylperoxide — so tert-butoxy and/or benzyl-type initiator/terminator fragments would inherently be present. An inherent, non-structurally-defined feature cannot confer patentability over a reference that necessarily produces it.

(b) Anticipation-adjacent reading of EP 682 102 A2 Example 1. Because Example 1 uses thermal-route PIBSA (chlorine-free), a polyoctadecene/MA copolymer (C18 olefin), and TEPA, at a polyamine charge ratio (~0.39 under the reference's own equivalence convention) that literally abuts the claimed 0.4 lower bound, a §102(b) anticipation argument is at least arguable for any claim broad enough to omit the succinic-ratio and copolymer-Mn limits. I flag this because the §103 case and the §102 case run through the same document — but I have not verified the exact claim text, so I cannot assert anticipation.

---

7. Rebuttal considerations the patentee would likely raise

1. Teaching away on polyisobutene Mn. The '892 Background cites Forbes & Neustadter, Tribology Vol. 5, No. 2, pp. 72–77 (1972), for the proposition that "maximum detergency performance is obtained when the polyisobutenyl group has a Mn of about 1300," and that Mn 2000+ succinimides are worse detergents. '321/'552 recite the same passage. This is the strongest nonobviousness argument available, but it is undercut by (i) '435's express counter-teaching of 1700–2400 as especially preferred, (ii) Roby, Kornbrekke & Supp, J. Soc. Tribologists and Lubrication Engineers Vol. 50(12), pp. 989–995 (Dec. 1994), which the '892 Background cites for the opposite conclusion (high-MW, ~2000 dalton side chains outperformed ~1000 dalton), and (iii) the settled rule that conflicting prior-art teachings do not establish nonobviousness where one reference squarely discloses the claim (In re Young, 927 F.2d 588 (Fed. Cir. 1991)).

2. Criticality of the 1.5:1 lower bound. The specification asserts a gel-avoidance threshold: "when less than 1.5 equivalents of alkenyl or alkylsuccinic acid derivative (A) per mole of unsaturated acidic reagent copolymer (B) are used then the polymer sometimes contains gels." This is a genuine in re "criticality" argument — but a threshold tied to a known, predictable failure mode (gelation) is typically treated as routine optimization rather than unexpected results. Note also that the patentee's own sibling disclosure, US 5,859,965 (family, not prior art), claims 0.5–10 for the same ratio, which tends to undercut the asserted criticality of 1.5.

3. Direction of the succinic-ratio teaching. The claims require a succinic ratio of only 1:1–2.5 (most preferably 1:1–1.2), whereas US 4,234,435 expressly requires ≥1.3 (pref. 1.5–2.5) and US 4,747,965 addresses only succinimides with >1.0 succinic groups per alkenyl substituent. The applicant could argue that '435 and '965 teach away from the low-succination, essentially mono-adducted PIBSA the claims use. This is the patentee's second-best argument; countering it requires showing that a 1:1–1.2 ratio PIBSA was itself conventional (which the thermal-process PIBSA literature — the '892 spec notes "the calculated succination ratio of material prepared by this process is typically 1.0 to 1.2" — strongly supports), rendering the ratio a mere known property of the chosen thermal route rather than a deliberate selection.

4. Secondary considerations. The '892 patent reports Panel Coker, Soot Thickening, and Sequence VE data. But the record here contains no evidence of commercial success, long-felt need, licensing, industry praise, or copying, and — as noted — the fluorocarbon-elastomer advantage may lack a nexus to the unpost-treated base claim. Absent such evidence, secondary considerations will not overcome a strong prima facie case.

---

8. Bottom line

The claims of US 6,358,892 are highly vulnerable under §103. The single most damaging combination is:

EP 0 682 102 A2 (the same three reactants, the same reaction, the same dispersant/VI-improver utility) in view of US 4,234,435 (the claimed polyalkene Mn windows and the express VI-credit teaching), further in view of US 5,112,507 (improved hydrolytic/shear stability from MA–olefin copolymer/polyamine succinimides) and US 5,334,321 / US 5,356,552 (cyclic-carbonate post-treatment of an Mn 2000–2700 PIBSA/polyamine succinimide expressly for fluorocarbon-elastomer compatibility).

Every claimed element maps to an express disclosure; the residual differences (the 1.5–10 charge ratio, the copolymer Mn 2000–4800, the 1:1–1.2 succinic ratio) are numerical ranges abutting or overlapping the prior art, supported by the specification's own predictability rationale, and the motivation is documented in the references themselves — including direct solutions to the exact two problems the applicant identified.

The patentee's only substantive rebuttals are the Forbes & Neustadter teaching-away argument on high Mn and the criticality argument on the 1.5:1 ratio; both are weakened by the '435/Roby counter-teachings and by the family's own broader ratio recitation, respectively. The composition claims (lube oil, concentrate, fuel) are, on this record, the weakest claims of all, since their numerical limits (1–5 wt%; 10–90 wt% concentrate; 10–10,000/30–2,000 ppm fuel) are copied substantially verbatim from the '321/'552 specification.

---

9. Confidence and open items

• High confidence: that EP 0 682 102 A2, US 4,234,435, US 5,112,507, US 5,334,321, US 5,356,552, US 4,612,132, US 4,747,965, and US 5,266,186 are qualifying prior art and that the motivation-to-combine case is strong. All are cited in the patent's own Prior Art section, and I independently confirmed the substance of EP 682 102 A2, US 4,234,435, US 5,112,507, and US 5,334,321/5,356,552 from primary documents.
• Moderate confidence: the exact numerical fit of EP 682 102 A2 Example 1 against the 0.4 polyamine ratio (my arithmetic from that reference's own equivalence convention; a different convention would change it). Also, the exact bibliographic date of EP 0 682 102 A2's §102(b) availability relative to the 1 Dec 1995 critical date is tight (published 15 Nov 1995 — available, but by a two-week margin, so if the effective priority date shifts at all this needs re-checking).
• Low confidence / not verified: verbatim claim language and claim numbering. The entire element map in §3 is reconstructed. Before relying on this analysis, pull the granted claims from USPTO PatentCenter or the patent PDF. I also did not verify the US filing date of the BP sibling US 5,719,108; if that date predates 1 Dec 1995, it would be an additional (and possibly earlier) §102(e) reference worth adding to the combinations above.