Mr O-Ring 442 Viton O-Ring 90A 7-1/4in ID Pack of 5 - High Temp Seal

In this review the Mr O-Ring 442 Viton O-Ring pack is examined for technicians, mechanics and DIYers who need a durable, high-temperature seal. The bottom line: this pack of five 90A durometer Viton o-rings stands out for broad chemical and temperature resistance, making it a dependable choice where petroleum, fuels, silicone oils or elevated heat are present. The reviewer found the size accuracy, material resilience and clear temperature specs to be the single biggest reasons to choose these o-rings for demanding sealing tasks.

Key Features

• Material: Fluorocarbon rubber (Viton/FKM) offers excellent resistance to oils, fuels and many organic solvents, reducing seal failures in chemical environments.
• Temperature Range: Rated from -26C (-15F) to 232C (450F), these o-rings maintain sealing performance across typical automotive and industrial temperature extremes.
• Durometer: A 90A hardness provides a firm cross-section that resists extrusion and maintains a reliable compression set for longer service life.
• Dimensional Accuracy: Nominal and actual dimensions (7-1/4in ID, 7-3/4in OD; actual 7.225in ID, 7.775in OD) match common AS568 sizing standards for predictable fit.
• Compatibility: Performs well with petroleum products, methanol or ethanol blends, diesel and biodiesel, and many greases, making it suitable for fuel systems and hydraulic seals.
• Pack Quantity: Supplied as a pack of five, useful for multiple service jobs or keeping spares on hand without buying large bulk quantities.

Who It's For

The Mr O-Ring 442 Viton o-rings are well suited to professional mechanics, maintenance technicians and advanced DIYers who work with fuel systems, hydraulic components or equipment exposed to high heat and aggressive fluids. Anyone needing AS568-compatible sizes and a firmer 90A compound will find these rings practical for repair and preventative maintenance.

Those who should look elsewhere include users who need a softer sealing material for low-pressure, delicate seals or applications below the stated temperature floor; silicone or nitrile alternatives may be a better fit where extreme cold flexibility or lower hardness is required.

Pros & Cons

Pros

• High chemical resistance to fuels, oils and many solvents reduces leak risk in harsh environments.
• Wide temperature tolerance allows use in both high-heat and common cold conditions without rapid degradation.
• Accurate AS568-equivalent dimensions help ensure a predictable fit in standardized grooves and housings.
• Pack of five offers value for multiple repairs or spare parts storage.

Cons

• The 90A hardness is relatively stiff and may not seal optimally in low-pressure or highly irregular surfaces that need a softer compound.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal Dimensions	7-1/4in ID, 7-3/4in OD, 1/4in CS
Actual Dimensions	7.225in ID, 7.775in OD, 0.275in CS
Metric Dimensions	183.52 mm ID, 197.50 mm OD, 6.99 mm CS
Temperature Range	-26C (-15F) to 232C (450F)
Pack Size	5 rings

Our Verdict

These Mr O-Ring 442 Viton rings are a practical, cost-effective choice for users needing durable seals in fuel, oil and high-temperature settings. The combination of 90A hardness, accurate AS568-compatible sizing and wide chemical compatibility makes them a strong value for maintenance shops and serious DIYers, while softer-seal users should consider alternate compounds.

Frequently Asked Questions

Are these o-rings resistant to gasoline and diesel?
Yes, the Viton FKM compound is specifically noted for good performance with petroleum products, gasoline blends and diesel.

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

Do the dimensions match AS568 sizes?
The product follows AS568-defined size standards with nominal and actual dimensions provided for predictable compatibility.