428 Viton O-Ring 75A 4-7/8in ID 5-3/8in OD - Durable Chemical Seal

In this review the 428 Viton O-ring is assessed for workshop and field sealing tasks where chemical and heat resistance matter most. The bottom line: this pack of ten O-rings is aimed at mechanics, machinists, and technicians who need a dependable seal that tolerates fuels, aromatic solvents and high temperatures. The reviewer found the single biggest reason to buy is the material: molded from Viton (fluorocarbon elastomer) with a 75A durometer, these O-rings hold shape and resist penetration while maintaining a reliable seal across a wide temperature range.

Key Features

• Material: Viton construction provides excellent resistance to fuels, aromatic and aliphatic hydrocarbons and many chemicals, making it suitable for fuel system and solvent-exposed seals.
• Temperature range: Rated from -15 degrees F to 400 degrees F so the O-ring stays flexible in cold starts and stable under sustained heat near engine or industrial equipment.
• Durometer: A 75A hardness balances flexibility and durability to resist penetration and maintain a long-lasting seal under compression.
• Dimensionally specific: With a 4-7/8in inner diameter, 5-3/8in outer diameter and 1/4in width these rings fit applications that require that size without need for trimming.
• Round cross-section: The classic round profile seals between overlapping cylindrical surfaces and is easy to install for common gland designs.
• Pack quantity: Available as a pack of ten, which offers spare parts on hand for repeated maintenance or multiple assemblies.

Who It's For

The 428 Viton O-ring is best for professionals and experienced DIYers working on fuel pumps, suppressor assemblies, hydraulic fittings and similar systems that encounter fuels, silicone oils, or chlorinated hydrocarbons. Its heat tolerance and compatibility with aromatic and aliphatic hydrocarbons make it practical for engine bays and industrial equipment.

Those who should look elsewhere include applications exposed to strong alkalis, ammonia gas, glycol-based brake fluids, or super-heated steam, since Viton is vulnerable to those media. Also, if you need an elastomer softer than 75A for ultra-low pressure sealing, a lower durometer material would be a better choice.

Pros & Cons

Pros

• Durable Viton compound that resists heat and many fuels, providing reliable long-term sealing.
• 75A hardness offers good resistance to penetration while remaining easy to compress into a gland.
• Accurate sizing (4-7/8in ID, 5-3/8in OD, 1/4in width) fits specific assemblies without modification.
• Pack of ten gives value for money and spare parts for maintenance.

Cons

• Not compatible with some chemicals like ammonia, strong alkalis or glycol-based brake fluids, so it is not universal.

Specifications

Material	Viton (fluorocarbon elastomer)
Color	Black
Inner diameter (ID)	4-7/8in
Outer diameter (OD)	5-3/8in
Width (cross-section)	1/4in
Durometer	75A
Temperature range	-15 degrees F to 400 degrees F

Our Verdict

For technicians who need a robust, heat- and fuel-resistant seal in a specific large size, this 428 Viton O-ring pack is a practical choice that delivers consistent performance and value. It is especially useful where durability and chemical resistance to fuels and aromatic solvents are required, but those working with alkalis or brake fluids should select a different compound.

Frequently Asked Questions

Can these O-rings handle gasoline and diesel?
Yes; Viton is compatible with fuels and aromatic hydrocarbons listed in the product description and is suitable for many fuel system seals.

Are these O-rings good for high-temperature engine use?
Yes; the rings are rated to 400 degrees F and maintain sealing performance in high-heat environments within that limit.

Will they resist weathering and ozone?
Viton offers good resistance to ozone and weathering, making these suitable for exposed applications as long as the chemical environment is compatible.