Oct . 21, 2025 12:20 Back to list

Genuine SEAL TYPE T OIL 90311-41020 | OEM Fit, Leak-Proof

Inside the shop: Genuine SEAL, TYPE T OIL 90311-41020

If you’ve torn down a Toyota driveline lately, you’ve probably handled this part. The Genuine SEAL Type T Oil 90311-41020 is one of those small, unsung components that decide whether the whole repair feels effortless or turns into a comeback. I’ve seen both. And, to be honest, the difference is usually materials and process control—not marketing.

What it is and why techs care

This is an OEM-spec Type T rotary shaft oil seal, ACM-based (polyacrylate rubber), color black, supplied new-in-box from Julu Industry Area, Xingtai City, Hebei Province, China 055250. The Genuine SEAL formulation is designed for hot, oily environments—gearboxes, axles, transfer cases—where fuels, ATF, or gear oil meet constant rotation and a bit of shaft runout. Many customers say it “just seats and seals,” which, frankly, is what you want.

Quick specs

Part name	Seal, Type T Oil
OEM code (Toyota)	90311-41020
Material	ACM (Polyacrylate Rubber) with steel insert; garter spring
Temperature range	≈ −20°C to +150°C in oil (real‑world use may vary)
Fluid compatibility	Engine oil, ATF, gear oils; good ozone/weather resistance
Lip style	Type T, spring-energized, unidirectional
Condition	OEM 100% genuine, new, unopened
Country of origin	China (Julu, Xingtai, Hebei)

How it’s made (short version)

Materials: ACM compound with carbon black and oil-resistant plasticizers; SPCC steel case; spring steel garter.
Methods: precision die-stamping of case, injection molding + vulcanization of ACM, flash trimming, lip micro-finish.
Testing: oil immersion per ASTM D471; compression set per ASTM D395; lip runout and leakage to ISO 6194/DIN 3760; hardness ≈ 70–75 Shore A.
Service life: around 120,000–160,000 km or 3,000–8,000 h in typical duty; depends on shaft finish (Ra ≤ 0.2–0.4 μm) and installation.
Industries: OEM assembly, dealer service, independent workshops, fleet maintenance, powertrain reman.

Real-world use, plus a quick case

One shop I follow swapped a leaking axle seal on a high‑mileage Toyota. The first aftermarket seal wept at 2,000 km—lip hardness drifted high, it seems. With the Genuine SEAL, same shaft and bore, leak-free after 15,000 km and counting. Not a lab study, sure, but it matches what many techs report.

Where it fits

Used in select Toyota driveline assemblies designated by 90311‑41020. Always verify dimensions and application in the EPC; similar part numbers aren’t interchangeable.

Why ACM here?

ACM balances heat (up to 150°C in oil), fuel/oil resistance, and cost. FKM would push temp higher, but for most axle/transfer outputs ACM is the pragmatic sweet spot.

Vendor comparison (field notes)

Vendor	Material & rating	Leak test	Notes
Genuine SEAL (OEM)	ACM, ≈ −20 to 150°C	Pass to ISO 6194 bench spec	Best fit/finish; consistent lip preload
Aftermarket (no‑name)	ACM/NBR, ≈ −20 to 120–140°C	Mixed; some seep at 0.05 MPa	Variable hardness, packaging differs
Premium aftermarket	ACM/FKM options	Usually meets DIN 3760	Good alternative if FKM needed

Customization and support

For special duty, vendors can tweak lip geometry, spring tension, or move to FKM. Bore coatings, anti-rotation ribs, and dust lips are also on the menu. Lead times vary; in my experience, pilot lots ship in 3–5 weeks.

Quality and certifications

Production commonly follows ISO 9001:2015; automotive programs target IATF 16949 audits. Batch traceability and RoHS statements are available upon request. Typical lab data show volume swell in IRM 903 oil ≤ 20% per ASTM D471 and hardness drift ≤ 5 Shore A after 70 h at 150°C.

Installation tip: Lightly oil the lip, check shaft Ra ≤ 0.4 μm, protect the lip over keyways, and seat square. Most “bad seals” I see were installed dry or cocked.

Authoritative citations

ISO 6194 (Rotary shaft lip seals) – Parts 1–4: terminology, dimensions, performance.
DIN 3760: Rotary shaft seals – requirements and testing.
ASTM D471: Standard Test Method for Rubber Property—Effect of Liquids.
ASTM D395: Compression Set of Rubber by Compression.
Toyota Electronic Parts Catalog (EPC) – Part No. 90311‑41020 application verification.
IATF 16949:2016 – Automotive Quality Management System Requirements.

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