Mr O-Ring 385 Viton O-Ring 90A Durometer, 16 in ID - Durable Seal

In this review the Mr O-Ring 385 Viton O-Ring is examined for workshop and industrial sealing needs; it is aimed at technicians, mechanics, and maintenance engineers who need a heat- and chemical-resistant seal in a standard AS568-equivalent size. The bottom line: this single-pack 90A durometer Viton o-ring delivers robust resistance to fuels, oils, ozone and high temperatures while holding tight dimensional tolerances, making it a dependable choice when compatibility and temperature performance are the top priorities.

Key Features

• Material: The Fluorocarbon rubber (Viton/FKM) formulation offers excellent resistance to fuels, mineral oils, and many organic solvents for longer service life in harsh fluids.
• Temperature range: Rated from -26C (-15F) up to 232C (450F), the o-ring handles very high air temperatures and many thermal cycles without rapid degradation.
• Hardness: The 90A durometer provides a firm seal that resists extrusion and maintains sealing force in pressurized assemblies.
• Size accuracy: Nominal 16 in ID with actual measured dimensions (15.955 in ID, 16.375 in OD) ensures consistent fit in housings designed to AS568 sizes.
• Chemical versatility: Performs well with petroleum products, diesel and biodiesel blends, methanol or ethanol blends, and many oils and greases, reducing the need for multiple compounds in inventory.
• Shelf life: Effectively unlimited shelf-life when stored properly, allowing spares to be stocked without rapid aging concerns.

Who It's For

The Mr O-Ring 385 is best for professionals and advanced DIYers who require a single, reliable o-ring for sealing applications exposed to high temperatures, fuels, or aggressive fluids; examples include fuel system maintenance, hydraulic components, and high-temp rotating or static seals. Its firm 90A hardness suits assemblies where extrusion resistance and predictable compression are important.

Those seeking a softer, low-compression set seal for delicate plastics or very low-temperature flexibility should look at lower durometer elastomers; likewise, this product is a single 1-pack, so operations needing bulk replacement parts may prefer multi-packs offered elsewhere.

Pros & Cons

Pros

• High chemical and temperature resistance from the Viton (FKM) compound reduces seal failure in aggressive environments.
• Tight actual dimensions and AS568 compatibility make installation straightforward in standard grooves and housings.
• 90A durometer hardness gives good extrusion resistance and durable sealing under pressure.

Cons

• 90A hardness is relatively firm and may not suit applications needing a softer seal for delicate mating surfaces.
• Sold as a single pack here, which may be less convenient for high-volume maintenance programs.

Specifications

Brand	Mr O-Ring
Material	Viton (Fluorocarbon rubber, FKM)
Durometer	90A
Nominal dimensions (ID / OD / CS)	16 in ID / 16-3/8 in OD / 3/16 in CS
Actual dimensions (ID / OD / CS)	15.955 in ID / 16.375 in OD / 0.210 in CS
Metric dimensions	405.26 mm ID / 415.92 mm OD / 5.33 mm CS
Temperature range	-26C (-15F) to 232C (450F)

Our Verdict

The Mr O-Ring 385 Viton 90A o-ring is a solid value for anyone needing a chemically resistant, high-temperature seal in a standard AS568 size; its measured dimensions and firm durometer make it particularly suitable for fuel systems, hydraulic parts, and high-temp assemblies. Buy it if compatibility with petroleum products and long-term stability are priorities; consider a different durometer or bulk option if you need softer material or higher quantity.

Frequently Asked Questions

Is this o-ring compatible with fuels and biodiesel?
Yes; the Viton compound is specified to perform well with petroleum products, diesel and biodiesel blends, and fuel blends with methanol or ethanol.

What size standards does this meet?
The o-ring is made to match AS568 size standards with nominal 16 in ID and corresponding OD and cross-section dimensions.

Can it handle high temperatures in engine or exhaust applications?
Yes; the operational range up to 232C (450F) makes it suitable for many high-temp air and engine-adjacent sealing tasks.