Mr O-Ring 336 Viton O-Ring 90A Durometer, 2-7/8 in ID (Pack of 10)

In this review the Mr O-Ring 336 Viton O-Ring is evaluated for technicians and hobbyists who need a reliable, high-temperature seal in fuel, oil, or chemical environments; the single biggest reason to buy is its durable 90A Viton compound that retains sealing properties across a very wide temperature range. The reviewer found these o-rings perform consistently in petroleum and hydraulic applications, and the pack of 10 offers practical value for maintenance or repair work where matching an AS568-equivalent size is important.

Key Features

• Material: Viton (FKM) offers excellent resistance to fuels, oils and many organic solvents, reducing seal degradation in harsh media.
• Durometer: The 90A hardness provides a firm, resilient seal that resists extrusion and maintains shape under compression.
• Temperature range: Rated from -26C (-15F) to 232C (450F), the ring works for high-temperature engine or industrial uses.
• Dimensions: Nominal 2-7/8 in ID and 3-1/4 in OD with actual closer tolerances, making it suitable where AS568 size fitment is required.
• Pack size: Sold in a pack of 10, convenient for repeat servicing and reduces the need to reorder frequently.
• Chemical resistance: Performs well with petroleum, diesel, biodiesel blends, methanol/ethanol blends and many oils, extending seal life in aggressive fluids.

Who It's For

The Mr O-Ring 336 Viton is aimed at mechanics, HVAC technicians, industrial maintenance crews and advanced DIYers who need a resilient seal that tolerates high heat and fuel exposure. Anyone replacing or stocking AS568-equivalent o-rings for pumps, valves or fuel system components will appreciate the predictable sizing and material properties.

Those who need a softer or more flexible seal for very low-temperature applications, or who require a specific proprietary compound or FDA food-grade certification, should look for specialty o-rings designed for those exact environments instead.

Pros & Cons

Pros

• High resistance to fuels, oils and many chemicals, so seals last longer in aggressive media.
• Wide operating temperature range allows use in high-heat engine and industrial settings.
• Consistent 90A hardness provides reliable sealing without excessive deformation.
• Pack of 10 gives good value for routine maintenance needs.

Cons

• 90A is relatively firm, which may be less ideal for applications that require a softer, low-temperature seal.
• Not presented as a food-grade or medical-grade material, so unsuitable where those certifications are required.

Specifications

Our Verdict

The Mr O-Ring 336 in 90A Viton is a solid choice for mechanics and maintenance professionals who need a durable, heat- and fuel-resistant seal in a commonly used size; the pack of 10 and AS568-equivalent dimensions make it practical and cost-effective for routine repairs. It is not intended for applications requiring softer seals or specialty certifications, but for general industrial and automotive sealing it represents good value and dependable performance.

Frequently Asked Questions

Are these o-rings compatible with gasoline and diesel?
Yes, the Viton compound resists petroleum products, diesel and common fuel blends, making them suitable for fuel system sealing.

Do the dimensions follow a standard size?
Yes, the rings meet AS568-equivalent sizing with nominal and actual dimensions provided for accurate fitment.

Can these be used at high temperatures?
Yes, they are rated to 232C (450F), suitable for many high-temperature engine and industrial applications.