Mr O-Ring 358 Viton O-Ring 90A Durometer Pack of 25 - High Temp Seal

In this review the Mr O-Ring 358 Viton O-Ring (90A durometer, pack of 25) is evaluated for workshop and industrial sealing tasks where temperature and chemical resistance matter. The bottom line: this set is best for technicians and maintenance professionals who need a reliable, high-temperature fluorocarbon o-ring in a standard AS568 size; the 90A hardness and Viton material make it especially suited to fuel, oil and high-heat applications where standard nitrile or silicone rings fail. The pack quantity and consistent actual dimensions give the confidence needed for repeated repairs and preventive maintenance.

Key Features

• Material: Viton (FKM) construction provides broad chemical resistance for use with petroleum products, fuels, hydraulic fluids and many solvents.
• Temperature range: Rated from -26C (-15F) to 232C (450F), which keeps seals stable across demanding hot and cold service conditions.
• Hardness: 90A durometer offers a firm seal that resists extrusion and maintains shape under pressure for many sealing applications.
• Size accuracy: Nominal and actual dimensions are provided, with actual ID 5.600in, OD 6.020in and CS 0.210in, reducing guesswork when replacing existing o-rings.
• Pack size: Sold as a pack of 25, which is convenient for shops and maintenance crews that perform frequent replacements or keep spares on hand.
• Standards: Manufactured to match common AS568 size standards, simplifying selection for standardized fittings and housings.

Who It's For

This o-ring set is aimed at mechanics, HVAC technicians, industrial maintenance teams and hobbyists who work with fuels, oils, hydraulic systems or high-temperature equipment. Those who need a resilient seal that tolerates ozone, weather and solvents will find the 358 Viton material appropriate for routine and demanding service.

It is not the best choice for applications that require very soft, low-durometer seals for delicate compression or for food-grade silicone-specific systems; users who need extreme low-temperature flexibility below -26C or certified food-contact materials should consider alternatives.

Pros & Cons

Pros

• Excellent chemical and high-temperature resistance thanks to Viton FKM material.
• Consistent actual dimensions (5.600in ID, 6.020in OD, 0.210in CS) make replacements straightforward.
• Pack of 25 supplies multiple repairs and saves time on repeat maintenance tasks.
• 90A durometer offers durable sealing against extrusion and pressurized environments.

Cons

• Relatively firm 90A hardness may be too stiff for applications that require softer, more flexible o-rings.
• Not specified as food-grade or FDA compliant, so unsuitable for food or medical contact without further verification.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal dimensions	5-5/8in ID, 6in OD, 3/16in CS
Actual dimensions	5.600in ID, 6.020in OD, 0.210in CS
Metric dimensions	142.24 mm ID, 152.90 mm OD, 5.33 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack quantity	25 rings

Our Verdict

The Mr O-Ring 358 Viton 90A pack is a practical, durable choice for maintenance professionals and workshops that need reliable seals for fuels, oils and high-temperature systems; the combination of Viton chemistry, clear actual dimensions and a 25-count pack make it good value for repair kits and preventive maintenance, provided a firm 90A hardness is acceptable for the application.

Frequently Asked Questions

Are these o-rings compatible with diesel and biodiesel blends?
Yes. Viton (FKM) is resistant to diesel and blends with biodiesel, making these o-rings suitable for such fuel systems.

Do the rings meet a standard size reference?
They are manufactured to match common AS568 size standards and list both nominal and actual dimensions for confirmation.

Can these be used at very high temperatures?
Yes. The specified temperature range goes up to 232C (450F), so they are suitable for many high-temperature sealing tasks.