Mr O-Ring 265 Viton O-Ring 7-3/4in ID 90A Pack of 10 - High Temp Seal

In this review the Mr O-Ring 265 Viton O-Ring pack is evaluated for mechanics, fabricators and hobbyists who need a reliable, high-temperature sealing solution. The bottom line: this pack of ten 90A durometer Viton o-rings delivers consistent dimensions and broad chemical resistance, making it a practical choice when sealing against fuels, oils or high heat is the priority. The reviewer found the nominal and actual sizes closely matched, the material felt firm and resilient, and the specified temperature range makes these o-rings suitable for demanding applications where durability and chemical resistance matter.

Key Features

• Material: Viton (FKM) offers excellent resistance to fuels, mineral oils and many solvents, reducing seal failures in harsh chemical environments.
• Durometer: 90A hardness gives a firm seal that resists extrusion and deformation under pressure while still compressing enough to maintain a leak-free joint.
• Size accuracy: Nominal 7-3/4in ID and 8in OD with actual measurements very close to spec, which simplifies replacement tasks without resizing concerns.
• Temperature range: Rated from -26C to 232C (-15F to 450F), suitable for high temperature air, engine compartments and many industrial systems.
• Pack quantity: Comes as a pack of 10, convenient for maintenance cycles or multiple repair points without frequent reordering.
• Standards: Made to the AS568 size standard so these o-rings fit common grooves and housings built to that specification.

Who It's For

This product is best for technicians, maintenance crews and DIY mechanics who need a dependable Viton seal for fuel systems, hydraulic fittings and high-temperature assemblies. The firm 90A durometer and broad chemical compatibility make it a practical choice where exposure to petroleum, biodiesel blends, methanol/ethanol and many oils is expected.

Those who need an ultra-soft seal for delicate low-pressure plumbing or very tight, low-torque fittings might prefer a lower-durometer elastomer. Also, if metric sizes are mandatory for an exact match, verify the listed metric dimensions before ordering.

Pros & Cons

Pros

• High chemical resistance reduces swelling or degradation in fuels, oils and many solvents.
• 90A durometer provides durable, extrusion-resistant sealing in higher pressure or high-temperature settings.
• Actual dimensions closely match nominal sizes, easing installation and replacement.
• Pack of 10 is cost-effective for service kits and multiple repairs.

Cons

• 90A is relatively firm and may be too stiff for applications that require a very soft seal.
• Viton can be more expensive than general-purpose elastomers, so it may be overkill for benign, low-temperature uses.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal ID x OD x CS	7-3/4in ID, 8in OD, 1/8in CS
Actual ID x OD x CS	7.734in ID, 8.012in OD, 0.139in CS
Metric dimensions	196.44 mm ID, 203.50 mm OD, 3.53 mm CS
Temperature range	-26C to 232C (-15F to 450F)
Pack quantity	10 o-rings

Our Verdict

The Mr O-Ring 265 Viton o-ring pack is a solid choice for anyone needing a high-temperature, chemically resistant seal in automotive, industrial or plumbing tasks. Its close-to-spec actual dimensions, 90A hardness and AS568 sizing make it reliable and easy to swap into existing hardware, offering good value when durability and compatibility are the priority.

Frequently Asked Questions

Are these o-rings suitable for fuel and oil exposure?
Yes. Viton (FKM) is formulated to resist fuels, diesel blends, mineral oil and many solvents, making these o-rings appropriate for such applications.

Do the actual dimensions match the nominal dimensions closely?
Yes. The product lists both nominal and actual sizes (for example 7.734in actual ID versus 7-3/4in nominal), so they are very close and should fit AS568 standard grooves.

Can these be used at high temperatures?
Yes. The rated temperature range is -26C to 232C (-15F to 450F), suitable for many high-temperature sealing needs.