Mr O-Ring 372 Viton O-Ring 90A, 8-3/4 in ID - Pack of 10

In this review the Mr O-Ring 372 Viton O-Ring pack is evaluated for technicians and DIYers who need heat- and chemical-resistant seals for engines, pumps, and industrial equipment. The bottom line: these 90A durometer Viton o-rings offer a reliable, compact solution when resistance to fuels, oil, high temperatures and ozone is essential. The pack of 10 and the near-standard dimensions make them a practical choice for replacements and maintenance, and the review focuses on durability, dimensional accuracy and where these o-rings are best used.

Key Features

• Material: Viton FKM construction provides exceptional resistance to high temperature and many aggressive chemicals, which means longer service life in harsh environments.
• Hardness: The 90A durometer gives a firm seal that resists extrusion and compression set under pressure, maintaining sealing performance over time.
• Dimensions: Nominal 8-3/4 in ID and 9-1/8 in OD with actual closer tolerances offer compatibility with fittings specified to these size standards.
• Temperature Range: Rated from -26C to 232C (-15F to 450F), allowing use in applications that cycle between low and very high temperatures.
• Chemical Compatibility: Performs well with petroleum fuels, biodiesel blends, methanol/ethanol blends, mineral oils and many solvents, so it suits varied fluid service.
• Pack Size: Supplied as a pack of 10 which is convenient for routine maintenance and reduces downtime by keeping spares on hand.

Who It's For

The Mr O-Ring 372 is aimed at maintenance technicians, mechanical workshops and hobbyists who work on fuel systems, hydraulic components, pumps or high-temperature seals and who need a compact, chemical-resistant o-ring that conforms to common size standards. The 90A hardness and Viton material make it a strong match for applications exposed to fuels, oils and elevated temperatures.

Those who should look elsewhere include users needing very soft, ultra-low pressure seals or applications requiring FDA food-grade elastomers; Viton is not the best choice for elastomer-flexible, low-friction needs or for some food-contact approvals.

Pros & Cons

Pros

• High chemical and heat resistance extends service life in demanding fuel and oil environments.
• 90A durometer balances firmness and sealing reliability for many mechanical applications.
• Pack of 10 provides ready spares for maintenance and reduces replacement wait time.
• Actual dimensions closely match nominal sizes for easier installation in standard grooves.

Cons

• Viton 90A is relatively stiff compared with softer elastomers, which may not suit very low-pressure sealing or delicate fittings.
• Not a specialized food-grade or ultra-low friction material, so it is unsuitable where those certifications are required.

Specifications

Our Verdict

The Mr O-Ring 372 Viton o-ring pack is a practical, cost-effective choice for professionals and tinkerers who need durable seals resistant to fuels, oils and high temperatures. Its 90A hardness and accurate sizing make it dependable for many industrial and automotive sealing tasks, and the pack of 10 is good value for maintenance programs that require ready spares.

Frequently Asked Questions

Are these o-rings compatible with gasoline and diesel?
Yes, the Viton compound is formulated to perform well with petroleum, gasoline, diesel and common fuel blends.

Will the 90A hardness compress properly for groove seals?
The 90A durometer is firm and resists excessive compression set; it is suitable for typical grooves where a resilient, durable seal is required.

Can these be used at high temperature continuously?
They are rated up to 232C (450F) and are suitable for high-temperature use, though continuous exposure at the upper limit depends on application specifics and should be validated.