356 Viton O-Ring 75A Durometer, 5-3/8in ID - Heat and Chemical

Our review of the 356 Viton O-ring finds it best suited for technicians and home mechanics who need a reliable replacement seal that resists heat, fuels and many solvents. The single biggest reason to buy is material performance: made from Viton fluorocarbon elastomer with a 75A durometer, this O-ring holds up across a broad temperature range and resists common hydrocarbon fuels, making it a practical choice where leak resistance and chemical compatibility matter.

Key Features

• Viton construction: Provides superior resistance to fuels, aromatic and aliphatic hydrocarbons, and many chlorinated solvents, reducing swell and degradation in demanding environments.
• Wide temperature range: Rated from -15 degrees F to 400 degrees F so it can be used in hot engine or industrial applications as well as cooler conditions without rapid hardening or softening.
• 75A durometer: The medium-hard Shore hardness offers good resistance to penetration and extrusion while still compressing to form effective leak-tight seals between overlapping cylindrical surfaces.
• Round cross-section: Classic O-ring geometry ensures reliable sealing in standard grooves and between mating cylinders for general hydraulic and pneumatic use.
• Pack of five: Multiple pieces in one purchase make it convenient for replacing several seals or keeping spares on hand for routine maintenance.

Who It's For

This O-ring is for professionals and hobbyists who need a robust replacement for fuel-system seals, hydraulic fittings, or barrel and bottle seals where compatibility with fuels and solvents is required. It is particularly useful for applications that see elevated temperatures or exposure to aromatic hydrocarbons.

It is not the best choice where the seal will sit in contact with strong alkalis, ammonia gas, glycol-based brake fluids, or super-heated steam, as Viton is vulnerable to those media; users working mainly with those chemicals should seek a material specified for that exposure.

Pros & Cons

Pros

• Excellent chemical and fuel resistance for a wide range of hydrocarbon-based fluids.
• Performs well at high temperatures up to 400 degrees F, maintaining shape and sealing ability.
• Customers report good fit and leak resistance in common replacement uses, offering solid value for money.

Cons

• Not compatible with low molecular weight organic acids, amines, strong alkalis or super-heated steam, limiting its use in some specialty chemical environments.

Specifications

Material	Viton (fluorocarbon elastomer)
Color	Black
Inner diameter	5-3/8 in
Outer diameter	5-3/4 in
Width / cross-section	3/16 in
Durometer	75A Shore
Temperature range	-15 degrees F to 400 degrees F

Our Verdict

This 356 Viton O-ring is a dependable, cost-effective replacement for fuel, hydraulic and general sealing jobs where hydrocarbon compatibility and high-temperature resilience are needed. For anyone replacing seals on fuel bottles, barrels or similar assemblies, it delivers consistent leak resistance and durability, though users handling strong acids, alkalis or steam should choose a different material.

Frequently Asked Questions

Is this O-ring suitable for fuel systems?
Yes. Viton is compatible with many fuels and aromatic hydrocarbons, making this O-ring suitable for most fuel-system sealing tasks.

Will it handle high temperatures?
Yes. The O-ring is rated to 400 degrees F, so it performs well in hot environments common to engines and industrial equipment.

Are there fluids to avoid?
Yes. Avoid prolonged contact with low molecular weight organic acids, ammonia, alkalis, amines, glycol-based brake fluids and super-heated steam, as Viton can be degraded by them.