Mr O-Ring 266 Viton O-Ring 90A Durometer 8in ID - Pack of 5

In this review the Mr O-Ring 266 Viton o-ring is evaluated for technicians and hobbyists who need a durable seal that resists fuels, oils and high temperature. The bottom line: this pack of five 90A durometer Viton o-rings is best for applications where chemical and temperature resistance matter more than extreme elasticity. The reviewer found the dimension accuracy and material properties useful for fuel systems, hydraulic fittings and high-temp static seals, making it a practical choice when a reliable, long-lived seal is the priority.

Key Features

• Material: Viton (FKM) construction provides excellent resistance to fuels, oils, aromatic solvents and many chemicals, reducing premature seal failure in aggressive fluids.
• Hardness: The 90A durometer offers firm compression set resistance for static seals that must retain shape under load and temperature cycles.
• Temperature range: Rated from -26C to 232C (-15F to 450F), making these o-rings suitable for high-temperature air and many heated fluid systems.
• Size accuracy: Nominal 8in ID and 8-1/4in OD with actual dimensions listed ensures a close fit to AS568 sizing and simplifies replacement planning.
• Pack quantity: Supplied as a pack of five, which is convenient for small maintenance jobs or sampling before larger purchases.
• Long shelf-life: Unlimited shelf-life means spares can be stored without concern for expiry, helpful for inventory and emergency kits.

Who It's For

This product is aimed at maintenance technicians, plumbing and hydraulic professionals, and DIYers who need o-rings that withstand petroleum products, biodiesel blends, silicone oils, and elevated temperatures. It is particularly suited to static sealing tasks, fuel line fittings, and applications where chemical compatibility with hydrocarbons and resistance to ozone are required.

Those who need very soft, flexible seals for dynamic rotary shafts or applications below the tested temperature range should consider a different compound or durometer. If extreme abrasion resistance or food-grade material is required, another specialized material would be a better fit.

Pros & Cons

Pros

• Excellent chemical resistance to petroleum, diesel, alcohol blends and many solvents, so it performs reliably in fuel and oil service.
• High temperature capability up to 232C (450F) makes it appropriate for hot environments and heated fluid systems.
• Accurate actual dimensions close to nominal sizes help ensure proper fit when replacing AS568-equivalent o-rings.
• Unlimited shelf-life and pack of five reduce waste and make spare management straightforward.

Cons

• At 90A durometer the o-ring is relatively firm, so it is less suitable for applications that require very soft, highly elastic seals or dynamic rotary use.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal dimensions	8in ID, 8-1/4in OD, 1/8in CS
Actual dimensions	7.984in ID, 8.262in OD, 0.139in CS
Metric dimensions	202.79 mm ID, 209.85 mm OD, 3.53 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack size	5 o-rings

Our Verdict

The Mr O-Ring 266 Viton 90A o-ring is a solid choice for anyone needing a chemically resistant, high-temperature static seal with reliable dimensional accuracy. For maintenance shops and field repairs it offers good value as a pack of five with an effectively unlimited shelf-life, though those needing softer dynamic seals should select a lower durometer or different compound.

Frequently Asked Questions

Are these o-rings compatible with gasoline and diesel?
Yes, Viton (FKM) is resistant to petroleum fuels, diesel and common fuel blends, making them suitable for fuel system sealing.

Will they work for high-temperature applications?
Yes, they are rated to 232C (450F), suitable for many high-temperature air and fluid sealing applications.

Do these match AS568 sizes?
The product is made to meet AS568 size standards and lists both nominal and actual dimensions to aid correct selection.