357 Viton O-Ring 75A Durometer, 5-1/2 in ID - Reliable Seal Pack

In this review the 357 Viton O-ring is presented as a practical replacement for equipment requiring chemical and heat resistance; the bottom line is that it is best for technicians and hobbyists who need a dependable, fuel- and chemical-resistant seal without elaborate specialty sizing. The pack of five offers ready spares, and the single biggest reason to buy is the material: made from Viton fluorocarbon elastomer that holds up across a wide temperature range and resists many fuels and solvents commonly encountered in hydraulics and small engine work.

Key Features

• Material: Viton fluorocarbon elastomer provides strong resistance to fuels, aromatic and aliphatic hydrocarbons, and many solvents, reducing seal degradation in harsh environments.
• Temperature range: Rated from -15 degrees F to 400 degrees F, which keeps seals reliable from cold storage to high-heat engine or industrial applications.
• Durometer: A 75A hardness gives a balance of flexibility and resistance to penetration for lasting compression set performance in dynamic and static seals.
• Cross-section shape: Round profile is designed to seal between cylindrical overlapping surfaces, making it suitable for bottle fittings, barrels, and similar joints.
• Standards: Meets the AS568A sizing standard, so it is interchangeable with commonly referenced O-ring specifications for easy replacement.
• Pack size: Supplied as a pack of five, providing spares for maintenance and reducing downtime when a replacement is needed.

Who It's For

This O-ring is aimed at mechanics, maintenance technicians, and DIYers who need a robust replacement for seals exposed to fuels, oils, and heat, such as fuel bottle fittings, firearm barrel seals, or small engine components. The pack size and standard sizing make it useful for stocking a workbench or kit.

Those who should look elsewhere include users needing compatibility with strong alkalis, ammonia gas, or glycol-based brake fluids, and applications that require very soft or very hard durometers outside the 75A range; specialty elastomers would be a better choice for those chemistries or hardness needs.

Pros & Cons

Pros

• Excellent chemical and fuel resistance for a wide range of common fluids, improving seal longevity.
• Wide usable temperature range that handles both low- and high-temperature environments without rapid failure.
• Standard AS568A sizing and round cross-section make replacements straightforward and compatible with many fittings.
• Pack of five provides value and immediate spares for maintenance tasks.

Cons

• Not suitable for exposure to low molecular organic acids, ammonia, strong alkalis, or glycol-based brake fluids, so compatibility must be checked.
• A single durometer (75A) may not be ideal where much softer or harder seals are required for specific clearances or dynamic sealing conditions.

Specifications

Material	Viton (fluorocarbon elastomer)
Color	Black
Inner Diameter (ID)	5-1/2 in
Outer Diameter (OD)	5-7/8 in
Width / Cross-section	3/16 in
Durometer	75A
Temperature Range	-15 degrees F to 400 degrees F

Our Verdict

The 357 Viton O-ring pack is a solid, cost-effective option for anyone needing a reliable seal that resists fuels, many solvents, and high heat; it is particularly strong as a replacement part for hydraulics, fuel fittings, and small engines. Buy this if you want standard AS568A sizing, durable Viton performance, and spare pieces on hand; avoid it only when your application involves incompatible chemicals or requires a different hardness.

Frequently Asked Questions

Will this O-ring resist gasoline and diesel?
Yes. Viton is compatible with many fuels and aromatic and aliphatic hydrocarbons, making it suitable for gasoline and diesel exposures.

Is this size compatible with common AS568 applications?
Yes. The ring meets AS568A sizing conventions and should interchange with matching AS568 standard grooves using the same ID and cross-section.

Can I use this O-ring with brake fluid or ammonia?
No. Viton is vulnerable to glycol-based brake fluids and ammonia gas, so choose a different elastomer for those fluids.