Automotive O-Rings

Category: Custom O-Rings & Rubber Seals

Hongjie supplies custom and standard automotive O-rings in AS568A and metric sizes. Production follows IATF 16949:2016 requirements, with PPAP documentation available for Tier 1 and OEM programs.

Engineering and procurement teams can send a drawing or legacy sample. Hongjie matches the compound, dimensions and tolerance to the fluid and temperature conditions of the actual application rather than supplying a generic assortment kit.

For flange and housing applications, see rubber sealing gaskets.

O-Rings by Vehicle System

Vehicle System	Sealing Demand	Recommended Compound
Fuel systems (injectors, fuel rails, filler necks)	Resistance to gasoline, ethanol blends, biodiesel	Fuel Resistant O-Rings
Engine oil & lubrication circuits	Long-term oil swell resistance at elevated temperature	Oil Resistant O-Rings
Brake & power steering fluid lines	Compatibility with glycol-based and mineral hydraulic fluids	Chemical Resistant O-Rings
Transmission & hydraulic lines	Pressure cycling, ATF exposure	Hydraulic O-Ring Seals
A/C, HVAC & coolant systems	Refrigerant permeation resistance, cold-flex sealing	Silicone O-Rings and NBR Rubber O-Rings
EV battery thermal management	Coolant-loop compatibility for pack thermal circuits — an emerging application evaluated case by case	EPDM Rubber Seals

Turbocharger with brown o-rings on a workbench

Spec Snapshot

Spec	Range
Inside diameter (ID)	From 0.60mm (miniature sizes) up through large-bore metric and AS568 profiles, per drawing
Cross-section	Standard AS568/metric cross-sections, confirmed against your drawing or sample
Durometer	40–90 Shore A
Tolerance class	Standard ±0.10mm to ±0.25mm (0–100mm dimension range), or Precision down to ±0.02mm

MOQ, tooling cost, and production lead time depend on part geometry and complexity — these are confirmed during quote review once we have your drawing. Functional prototypes are separately confirmed at 3–5 business days.

Materials We Supply for Automotive O-Rings

Compound-to-fluid compatibility is confirmed against our engineering validation program's testing library of 500+ fluids, gases, and chemicals before a material is recommended.

NBR
the standard choice for fuel, oil, and general hydraulic circuits within our overall –60°C to +325°C compound range; typically selected for moderate-heat services.
FKM (Viton)
chemical and heat resistance for fuel systems, power steering, and turbo/EGR zones, selected toward the high-heat end of our rated range; see Viton O-Rings.
HNBR
the automotive A/C standard for R-134a/R-1234yf refrigerant exposure, rated for sustained moderate-to-high heat.
Silicone (VMQ)
cold-flex stability at the low end of our rated range plus continued flexibility at heat, used for coolant and HVAC seals.
EPDM
weathering and coolant resistance across a wide service range where petroleum-oil exposure isn't a factor; for flat gasket formats see EPDM Rubber Gaskets.

Precision & Sizing — AS568 and Custom Tolerances

Standard O-rings are supplied against AS568 dash sizes and metric equivalents. Custom parts hold standard tolerance of ±0.10mm on 0–10mm dimensions (up to ±0.25mm at 50–100mm), tightening to ±0.02mm on precision work, with a target Cpk >1.33 for consistency across production runs. Custom-molded automotive O-rings built from a drawing or sample go through the same custom rubber O-ring process as standard sizes.

Quality

Quality & Automotive Compliance

Production runs under IATF 16949:2016, with PPAP documentation packages available on request for Tier 1 and OEM buyers. Dimensional and material testing — hardness, tensile strength, compression set, chemical resistance, and accelerated aging — is performed in-house. For other automotive sealing and component needs, see automotive rubber seals and automotive rubber parts.

Request a Quote

Get a Quote for Custom Automotive O-Rings

Upload your drawing for a project quote, or talk to an engineer about compound selection, groove design, or tolerance requirements before you finalize a spec.

FAQ

Frequently Asked Questions

What documentation ships with production lots?

PPAP documentation packages — dimensional reports, material certifications, and process capability data — are available on request for Tier 1 and OEM production programs.

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

NBR is the standard oil-resistant compound for most engine oil circuits; HNBR or FKM are stepped up for higher operating temperatures or longer service intervals.

How do I know my O-ring size?

Measure inside diameter and cross-section, then match against AS568 dash numbers or metric tables — or send the original part/drawing and we'll confirm the size and compound.

What is the best material for automotive O-rings?

It depends on the system: NBR for fuel and oil, FKM/Viton for fuel and power steering under heat, HNBR for A/C refrigerant, and silicone for coolant and HVAC applications.