Mr O-Ring 360 Viton O-Ring 90A 5-7/8in ID Pack of 5 - High Temp Seal

In this review the Mr O-Ring 360 Viton O-Ring (90A) is judged on durability and chemical resistance for demanding sealing tasks; it is best for technicians, mechanics, and hobbyists who need a compact, high-temperature seal that resists fuels and solvents. The bottom line: this pack of five black Viton o-rings delivers reliable sealing across a wide temperature and chemical range, making it a practical choice when long-term resistance to petroleum, alcohol blends, and many solvents matters most.

Key Features

• Material: Viton (FKM) construction provides excellent resistance to high temperature, ozone, weathering and many organic solvents, protecting seals in harsh environments.
• Durometer: 90A hardness gives a firm, durable seal that resists extrusion while maintaining elasticity across the rated temperature range.
• Size accuracy: Nominal and actual dimensions are listed, so installers can match 5-7/8in ID applications with confidence using the provided actual ID of 5.850in and OD of 6.270in.
• Chemical compatibility: Performs well with petroleum products, methanol or ethanol blends, diesel and biodiesel blends, mineral and silicone oils and greases, making it versatile for fuel and fluid systems.
• Temperature range: Wide service range from -26C (-15F) to 232C (450F) for use in both cold and very high temperature air and fluid environments.
• Pack size: Supplied as a pack of five which is practical for maintenance tasks or multiple assemblies without buying bulk inventory.

Who It's For

This Viton o-ring is aimed at professionals and serious DIYers who work with engines, pumps, valves and hydraulic or fuel systems where exposure to fuels, oils and elevated temperatures is expected. It is useful for maintenance shops, industrial technicians and anyone replacing worn seals to restore reliable performance.

Those who primarily need soft, low-pressure sealing for food-grade or potable water systems may want to look at alternative elastomers designed for those approvals, while projects requiring extremely soft or ultra-low temperature flexibility might prefer a lower durometer or different compound.

Pros & Cons

Pros

• Excellent chemical and high-temperature resistance for fuel and solvent-exposed applications.
• Firm 90A hardness resists extrusion and maintains a reliable seal under pressure and temperature cycles.
• Accurate actual and metric dimensions reduce fitment guesswork during replacement.

Cons

• 90A durometer is relatively stiff, so it may not be ideal for applications that require very soft, low-compression sealing.

Specifications

Brand	Mr O-Ring
Material	Viton (FKM)
Durometer	90A
Nominal Size	5-7/8in ID, 6-1/4in OD, 3/16in CS
Actual Size	5.850in ID, 6.270in OD, 0.210in CS
Temperature Range	-26C (-15F) to 232C (450F)
Pack Quantity	5

Our Verdict

The Mr O-Ring 360 Viton 90A pack of five is a strong choice for users needing a durable, high-temperature o-ring with broad chemical compatibility; its accurate sizing and firm durometer make it good value for repair shops and industrial use where long-term resistance to fuels and oils is required.

Frequently Asked Questions

Are these o-rings suitable for fuel systems?
Yes, the Viton compound is compatible with petroleum fuels and blends including methanol/ethanol and biodiesel in many service conditions.

Will the 90A hardness seal under high pressure?
The 90A durometer offers good extrusion resistance and performs well under typical pump and valve pressures, though seal design and groove tolerances also matter.

What temperatures can these o-rings handle?
They operate from about -26C (-15F) up to 232C (450F), covering most engine, exhaust and high-temperature fluid applications.