M2.5x113 Viton O-Ring 75A Durometer - Durable Chemical Seal

In this review the M2.5x113 Viton O-Ring is assessed for practical sealing tasks where chemical and heat resistance matter. The bottom line: this pack of ten O-rings is aimed at technicians, hobbyists, and mechanics who need a reliable, compact seal for cylindrical joints and threaded protectors, and its single biggest advantage is the Viton compound that maintains sealing performance across a wide temperature range. The reviewer found these rings particularly useful where fuel, oil, or aromatic hydrocarbons are present and where a 75A hardness balances flexibility and compression set resistance.

Key Features

• Material: Made from Viton fluorocarbon elastomer, the O-ring resists many fuels and chemicals commonly encountered in automotive and industrial service.
• Temperature range: Rated for use over a broad span, the O-ring handles both subfreezing and elevated temperatures typical in engine and hydraulic environments.
• Durometer 75A: The 75A hardness provides a firm seal that holds shape under compression while remaining compliant enough for threaded and cylindrical mating surfaces.
• Round cross-section: The classic round profile creates an effective seal between overlapping cylindrical parts such as barrels, shafts, and housings.
• Pack of 10: Supplied in a multi-pack that offers spare parts for repeated installations or for protecting multiple threaded barrels or fittings.

Who It's For

This O-ring is best for mechanics, maintenance technicians, and DIYers who service fuel systems, carburetors, hydraulic fittings, or threaded protectors and need a resilient seal against hydrocarbons and oils. It is also useful for projects where compatibility with silicone oils and many aromatic and aliphatic hydrocarbons is required.

Those who should look elsewhere include users needing compatibility with strong alkalis, ammonia gas, or glycol-based brake fluids, since Viton is vulnerable to those media; likewise, if an ultra-soft or very hard compound is required, different durometer options would be a better fit.

Pros & Cons

Pros

• Good chemical and fuel resistance from the Viton material for many industrial fluids and fuels.
• Wide operational temperature capability useful in engine and hot-process contexts.
• 75A hardness strikes a practical balance for sealing threaded barrels and cylindrical joints without excessive deformation.
• Customers report reliable fit and value, with specific success on Springfield threaded barrels and DRZ 400 carburetor seats.

Cons

• Not compatible with strong alkalis, amines, or glycol-based brake fluids, so it is not universally chemical-proof.
• Only one size and durometer in the pack, so it does not cover other bore or hardness needs.

Specifications

Material	Viton (fluorocarbon elastomer)
Inner diameter (ID)	113 mm
Outer diameter (OD)	118 mm
Cross-section width	2.5 mm
Durometer	75A
Temperature range	-15 degrees F (-26 degrees C) to 400 degrees F (205 degrees C)
Pack quantity	10 O-rings

Our Verdict

The M2.5x113 Viton O-Ring is a practical, cost-effective choice for anyone needing a durable seal against fuels, oils, and many chemicals at varied temperatures. It is particularly good value for repairs and maintenance where a 75A hardness and the specified diameter match the application; however, those requiring resistance to alkalis or glycol-based fluids should consider alternate materials.

Frequently Asked Questions

Are these O-rings suitable for fuel applications?
Yes; Viton offers good resistance to many fuels, aromatic and aliphatic hydrocarbons, and silicone oils, making these rings suitable for many fuel-related seals.

Will the 75A hardness work on threaded barrel protectors?
Customers report the 75A durometer works well to keep thread protectors and similar fittings in place without excessive deformation.

Can these O-rings be used with brake fluid?
No; Viton is vulnerable to glycol-based brake fluids, so these O-rings are not recommended for that use.