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Oil Resistant O-Rings

Category: Custom O-Rings & Rubber Seals

Oil-resistant O-rings for engines, hydraulic systems, gearboxes and lubricating-oil applications are molded in NBR, FKM/Viton, HNBR and polyurethane. AS568A, metric and custom sizes are available, with tolerances down to ±0.02 mm. Request a quote with your oil type, operating temperature and drawing for material and pricing recommendations.

Oil resistance depends on compound chemistry, not the ring shape or brand. The correct grade must match the oil base stock, temperature and additive package; the wrong NBR grade may swell, soften and lose its seal. Material selection should therefore come before sizing and tooling.

Which Material Actually Resists Your Oil?

Oil compatibility depends on the oil base, operating temperature and additive package. The table below summarizes typical reference ranges for four common oil-contact O-ring compounds. Actual performance should be confirmed against the specific oil and compound grade.

Compound	Oil Types Handled	Temperature Range	Typical ASTM D471 Volume Swell (IRM 903 Oil)	Durometer Options	Relative Cost
NBR (Nitrile)	Mineral/petroleum oils, engine oil, general lube oil	−30°C to +120°C	0% to +30%	60–90 Shore A (70A most common)	Economy
HNBR	Engine oil, gear oil, synthetic lubricants, additive-heavy oils	−25°C to +150°C	0% to +15%	70–90 Shore A	Mid-tier
FKM (Viton)	Hot oils, synthetic lubricants, aggressive-additive oils	−20°C to +200°C	−5% to +5%	70–90 Shore A	Premium
Polyurethane (AU/EU)	Hydraulic oils, abrasive-oil environments	−30°C to +80°C	0% to +20%	80–95 Shore A	Mid-tier

NBR (Nitrile)

The usual starting point for mineral and petroleum-based oils at moderate temperatures. ACN content affects the balance between oil resistance and low-temperature flexibility.

HNBR

A step up from NBR when the oil runs hotter or contains aggressive additives. It offers better resistance to oxidation, compression set and long-term heat exposure.

FKM (Viton)

Best suited to high temperatures and severe additive or chemical exposure. Its lower swell and wider chemical range come with a higher material cost.

Polyurethane (AU/EU)

Useful in cooler hydraulic systems with frequent motion, abrasion or particulate contamination.

colorful rubber o-rings in various sizes

EPDM and silicone are better suited to water, steam and weathering exposure, but generally perform poorly with petroleum-based oils. The compound family should therefore be specified clearly rather than listed only as “rubber.”

For a broader comparison of NBR, FKM and EPDM, see NBR vs. FKM vs. EPDM O-ring compound selection.

APPLICATIONS

Oil-Contact Sealing by Application

Material selection depends on the oil type, temperature, pressure, motion and additive package in the application.

View O-Ring Options

Precision & Manufacturing Capability

Oil-resistant O-rings are produced by injection or compression molding in NBR, FKM/Viton, HNBR and polyurethane. Standard AS568A and metric sizes are available, along with custom cross-sections and inside diameters based on your CAD drawing.

Extrusion supports custom oil-resistant profiles and sealing strips beyond round O-rings. Rubber-to-metal bonding is also available when the oil seal forms part of a larger bonded assembly.

Durometer is selected by duty cycle, not by default:

Durometer (Shore A)	Typical Use
70	General-purpose oil seal — the most common O-ring hardness
80	Higher pressure retention, reduced extrusion under load
90	High-pressure dynamic seals, abrasion-prone hydraulic service

conveyor belts moving yellow rings in a factory

More than 3,500 existing mold tools support standard AS568A and metric sizes, helping reduce tooling cost and lead time. For non-standard geometries, a team of more than 25 engineers provides 3D CAD modeling and FEA review for groove fit, squeeze and extrusion gap.

Production runs on a semi-automated line in an 11,000 m² facility under SPC and Six Sigma methods, with a target of Cpk > 1.33 across production runs.

Functional prototypes are typically available within 3–5 business days after drawing approval. For more detail, see the engineering and mold design page and our guide to injection and compression molding for rubber parts.

colorful plastic rings in assorted sizes and colors

Testing & Fluid Compatibility Validation

Compound selection starts with the actual exposure conditions, not a datasheet alone. Hongjie tests materials against 500+ fluids, gases, and chemicals, including oil-based fluids, residual fuel, cleaning solvents, and coolant splash. Engineering support is available when an oil or blend falls outside the standard reference fluids.

Qualification testing may include:

Hardness
Tensile strength
Compression set
Accelerated aging
Fluid-resistance testing

Production operates under IATF 16949:2016 and ISO 13485:2016 certification. FDA- and NSF-compliant grades are available when oil-contact seals also require food, beverage, or medical compliance. Production lots follow documented acceptance sampling, with SPC and Cpk targets applied throughout the manufacturing process.

Custom Sizing & Compound Options

Standard AS568A and metric sizing
Plus fully custom ID/OD/cross-section built to your drawing.
Durometer range
From 60 to 95 Shore A depending on compound (70/80/90 Shore A cover most oil-contact applications).
FDA/NSF grades
FDA- and NSF-compliant material grades where the seal also contacts food-grade or beverage-grade oils.
Color and compound matching
Drawing on 200+ proprietary rubber compound formulations.
Bonded configurations
Rubber-to-metal bonded configurations where the oil-resistant seal is part of a bonded assembly.
Existing tooling
Access to 3,500+ existing mold tools for standard dash sizes, alongside new tooling for custom geometries.

MOQ and mass-production lead time are confirmed per drawing, compound, and order quantity — include your target volume in the RFQ for an exact figure. Prototype turnaround of 3–5 business days ahead of any production commitment.

Hongjie has manufactured rubber sealing components since 2001, exporting to 45+ countries and delivering 50M+ precision-inspected seals annually to global Tier-1 suppliers, with company and facility detail available on the about page. That production history is one input into a sourcing decision — the compound match to your specific oil is still the one that determines whether the seal actually holds.

Request a Quote

Request an Oil-Resistant O-Ring Quote

To get an accurate quote and material recommendation, include in your RFQ: the specific oil type (engine, gear, hydraulic, synthetic lube), operating temperature range, system pressure, target durometer, and dimensions or a CAD drawing. Upload the drawing and spec for an OEM quote — a functional prototype can typically be turned around in 3–5 business days for validation before mass-production tooling and MOQ are finalized.

Request a quote with your oil-contact application details.

FAQ

Frequently Asked Questions

What type of O-ring is best for engine oil?

NBR is the standard default for engine oil at moderate temperatures (−30°C to +120°C). Step up to HNBR (to +150°C) or FKM/Viton (to +200°C) when the same engine runs hotter or uses a synthetic oil formulation that attacks nitrile faster.

Are rubber O-rings good for oil?

“Rubber” isn't one spec — EPDM and silicone swell badly in oil and are a poor choice, while NBR, HNBR, and FKM are the compounds actually formulated for oil contact, each with progressively higher temperature and chemical resistance.

Can you use Viton O-rings for oil?

Yes. FKM/Viton handles oil exposure with very low volume swell (typically −5% to +5% in IRM 903 oil) and tolerates temperatures up to roughly +200°C, at a higher material cost than NBR — worth it when oil temperature or additive severity exceeds NBR's range.