Mr O-Ring 435 Viton O-Ring 90A Durometer - Pack of 5

In this review of the Mr O-Ring 435 Viton O-Ring pack, the bottom line is simple: this set is for technicians and hobbyists who need a reliable, high-temperature sealing solution in a common AS568 size. The reviewer found the 90A durometer Viton (FKM) material especially useful where resistance to fuels, oils, ozone and heat is required, and the pack of five covers multiple service replacements without overbuying. For those working with petroleum products, biodiesel blends, or high-vacuum and high-temperature air systems, these o-rings deliver consistent dimensions and long-term chemical resistance that justify choosing them over general-purpose elastomers.

Key Features

• Material: Viton (Fluorocarbon rubber) provides exceptional resistance to fuels, mineral oils, hydraulic fluids and many organic solvents, reducing seal failures in aggressive environments.
• Hardness: The 90A durometer offers a firm sealing surface that holds shape under compression while still conforming to mating surfaces for reliable sealing.
• Temperature Range: Usable from -26C (-15F) to 232C (450F), allowing service in both cold-start and very high-temperature applications without rapid degradation.
• Size Accuracy: Nominal and actual dimensions are close (5-3/4 in ID nominal; actual 5.725 in ID), helping installers match AS568 sizes and avoid rework.
• Pack Quantity: Sold as a pack of 5, which is convenient for routine maintenance or spare parts kits without excess inventory.

Who It's For

This product is aimed at maintenance technicians, marine and automotive professionals, and industrial users who need an AS568-compatible o-ring that stands up to fuels, high temperatures and harsh chemicals. The combination of Viton material and 90A hardness is particularly suited to seal components exposed to petroleum products, biodiesel blends, silicone greases, ozone and weathering.

Those who should look elsewhere include applications requiring very soft elastomers for low-load static seals or systems with strong bases that specifically call for different compounds; also, if a bulk quantity or multiple sizes are needed, a larger pack or assorted kit might be more economical.

Pros & Cons

Pros

• High chemical resistance to fuels, oils and many solvents improves longevity in harsh service.
• Wide operating temperature range supports both cold and very hot environments.
• Accurate actual dimensions and AS568 sizing make replacements straightforward.
• Pack of five balances spare availability with modest inventory needs.

Cons

• Higher durometer and Viton cost make it less ideal for very low-stress or cost-sensitive sealing where cheaper elastomers suffice.

Specifications

Our Verdict

The Mr O-Ring 435 Viton 90A pack is a sensible purchase for professionals and hobbyists who need durable, chemical-resistant o-rings in a common AS568 size. Its combination of accurate sizing, high-temperature tolerance and broad chemical compatibility makes it good value for repair kits and routine maintenance where reliability matters.

Frequently Asked Questions

Are these o-rings compatible with gasoline and diesel?
Yes; Viton FKM is compatible with petroleum products, diesel and blends with biodiesel as noted in the material characteristics.

Do the rings conform to standard AS568 sizes?
Yes; these o-rings are manufactured to meet AS568 size standards with closely matching actual dimensions.

What environments are they not ideal for?
They perform poorly in strong bases or applications that require very soft elastomers; in those cases select a different compound.