Mr O-Ring 362 Viton O-Ring 90A, 6-1/4in ID Pack of 5 - High Temp Seal

In this review the Mr O-Ring 362 Viton o-ring is evaluated for mechanics, hobbyists and maintenance pros who need a durable, high-temperature seal. The bottom line: this pack of five 90A durometer Viton o-rings stands out for chemical and heat resistance, making it a practical choice where exposure to fuels, oils or high heat is expected. The reviewer found the dimensional accuracy and material properties appropriate for routine service and many industrial sealing tasks.

Key Features

• Material: Viton (fluorocarbon rubber) provides exceptional resistance to fuels, mineral oils and many organic solvents, so seals last longer in aggressive fluids.
• Hardness: 90A durometer gives a firm cross-section that maintains shape under compression while still sealing reliably across a wide temperature range.
• Temperature Range: Rated from -26C to 232C (-15F to 450F), which makes these o-rings suitable for high-temp air and hot fluid applications.
• Size Accuracy: Actual dimensions closely match nominal (6.225in ID, 6.645in OD, 0.210in CS) so replacements fit standard grooves specified by size standards.
• Pack Quantity: Sold as a pack of 5, offering spare parts for maintenance cycles or multiple assemblies without buying bulk.
• Chemical Compatibility: Performs well with petroleum, diesel/biodiesel blends, methanol/ethanol blends and many oils, reducing unexpected failures in mixed-fuel systems.

Who It's For

This product is targeted at automotive technicians, equipment maintenance teams, and do-it-yourselfers who need reliable seals in fuel systems, hydraulic lines or high-temperature environments. The 90A hardness and Viton compound suit applications where exposure to fuels, mineral oils and elevated temperatures are common.

Those who need very soft or food-grade elastomers, or who require extreme low-temperature flexibility below -26C, should consider alternative materials. Also, if a custom size outside AS568-like ranges is required, a different supplier or custom molding may be necessary.

Pros & Cons

Pros

• Excellent chemical resistance to fuels, oils and many solvents, reducing swelling and degradation.
• High temperature tolerance up to 232C (450F) for demanding thermal environments.
• Accurate actual dimensions make replacement straightforward for standard grooves and fittings.
• Pack of five gives immediate spares for maintenance without excess inventory.

Cons

• 90A hardness is relatively firm and may not seal as well in extremely low-pressure or flimsy-surface applications compared with softer compounds.
• Viton is not suited for all aggressive chemistries (some perfluorinated solvents may require specialty elastomers).

Specifications

Material	Viton (Fluorocarbon rubber, FKM)
Durometer	90A
Nominal Size	6-1/4in ID, 6-5/8in OD, 3/16in CS
Actual Size	6.225in ID, 6.645in OD, 0.210in CS
Metric Size	158.12 mm ID, 168.78 mm OD, 5.33 mm CS
Temperature Range	-26C (-15F) to 232C (450F)
Pack Quantity	5 pieces

Our Verdict

The Mr O-Ring 362 Viton 90A is a sensible, cost-effective choice for anyone needing reliable seals that resist fuel, oil and high temperatures. It is especially valuable for routine maintenance and repairs where AS568-like sizing and dimensional accuracy matter. For users requiring softer seals or extreme low-temperature flexibility, consider alternate compounds, but for most industrial and automotive sealing tasks this pack offers good value.

Frequently Asked Questions

Are these o-rings compatible with diesel and biodiesel?
Yes, the Viton compound performs well with diesel and biodiesel blends and resists degradation from mineral oil and fuel exposure.

What temperature range can these o-rings handle?
They are rated from -26C (-15F) up to 232C (450F), suitable for high-temperature applications.

Do the actual dimensions match the nominal size?
Yes, the listed actual dimensions (6.225in ID, 6.645in OD, 0.210in CS) closely match the nominal sizes for proper replacement fit.