Mr O-Ring 358 Viton O-Ring 90A Durometer Pack of 10 - High Temp Seal

In this review the Mr O-Ring 358 Viton O-Ring (pack of 10) is examined for technicians and hobbyists who need a durable, high-temperature seal. The bottom line: this 90A durometer Viton o-ring is best for applications exposed to fuels, oils, and elevated temperatures because its material resists petroleum, biodiesel blends, silicone oils, ozone and weather, and holds dimensional stability across a wide operating range; the pack of 10 provides spare parts for maintenance without buying single pieces.

Key Features

• Material: Made from Viton (FKM), the compound provides strong resistance to petroleum products, fuels and many solvents for longer service life.
• Hardness: The 90A durometer gives a firm seal profile that resists extrusion and maintains contact under pressure in static and low-dynamic applications.
• Temperature range: Rated from -26C (-15F) to 232C (450F), suitable for very high temperature air and systems exposed to heat cycles.
• Size accuracy: Nominal and actual dimensions are provided so installers can confirm fit: 5-5/8in ID nominal with actual 5.600in ID and 6.020in OD.
• Versatility: Performs well with diesel, biodiesel blends, methanol/ethanol blends, mineral oil, silicone grease and strong acids in many sealing roles.
• Pack quantity: Sold as a pack of 10 which helps shops and maintenance crews keep spares on hand to reduce downtime.

Who It's For

The Mr O-Ring 358 Viton is aimed at maintenance technicians, plumbers, and equipment builders who require a resilient seal for fuel systems, hydraulic fittings or high-temperature housings. Its compatibility with petroleum products and wide temperature tolerance makes it a practical choice for industrial and automotive service kits.

Those who need extremely soft, low-durometer sealing for delicate low-pressure applications or food-grade elastomers should look elsewhere; Viton is a high-performance FKM suited to chemical and heat resistance rather than flexible low-force sealing or certified food contact uses.

Pros & Cons

Pros

• Excellent chemical resistance to fuels, oils and many solvents for longer service life in aggressive fluids.
• High temperature rating up to 232C (450F) allows use in hot air and elevated-temperature environments.
• 90A durometer offers firm compression resilience that resists extrusion in many static seal installations.
• Pack of 10 provides convenient spares for repairs and routine maintenance.

Cons

• Higher hardness means it is less suited to low-pressure, low-force sealing where a softer compound would seal better.

Specifications

Brand	Mr O-Ring
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)

Our Verdict

The Mr O-Ring 358 Viton 90A pack of 10 is a reliable, cost-effective choice for professionals who need a durable seal resistant to fuels, oils and high temperatures. It is good value for maintenance crews and equipment builders who require consistent dimensions and chemical resistance, though those needing very soft seals should consider a different compound.

Frequently Asked Questions

Is this o-ring compatible with diesel and biodiesel blends?
Yes. The Viton formulation is rated for petroleum products including diesel and blends with biodiesel.

What are the actual dimensions to confirm fit?
The actual dimensions are 5.600in ID, 6.020in OD and 0.210in cross section.

Can it be used at high temperatures?
Yes. The operating temperature range is -26C (-15F) to 232C (450F), suitable for high temperature applications.