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The Best Grease For Your O-Ring

O-rings are mechanical gaskets used to connect two parts of a machine, engine or other mechanical assemblies. They seal and fill the space between parts, creating a joint as they are compressed between the two components, often in a groove of one of the parts.

They prevent the leakage or ingress of particles, vapours and fluids, protecting the joint to ensure function and safety as intended. O-rings are usually made from elastomers like silicones and synthetic rubber, such as nitrile and EPDM.

O-rings should be greased regularly. Keeping O-rings lubricated is essential to maintain the function of the seal, extend service life, and prevent malfunction when a seal is blown. Lubrication protects the part through general water resistance, the minimisation of frictional forces, and the prevention of atmospheric degradation.

Choice of Lubricant

grease and components
Many types of lubricants can be used on O-rings, though pose health and safety concerns along with potential damage to the rubber O-ring. Petroleum grease, for example, may cause elastomeric rubber to degrade, swell or dry out. Most lithium greases are petroleum-based, so run the risk of the O-ring cracking, leaking and losing effectiveness. Solvents are sometimes used on O-rings, but contain high VOCs, while soap and water can be notoriously inconsistent in practice.

The best O-ring grease tends to be from a synthetic lubricant, particularly silicone-based and ester-based greases, as O-rings are often developed from synthetic compounds. They boast protection, they are waterproof and are also easy to use. Synthetic lubricants also reduce friction, have low volatility, and are useful at extreme temperatures, maintaining stability in high temperatures and fluidity in low temperatures.

Silicone grease is safe as well as effective on O-rings and rubber seals, posing no health risks or contamination by contact when using your hands for application. It can be used on rubber and plastic without the risk of damage. PTFE grease is an alternative option for lubricating O-rings. Its chemical inertia means it will not react with most materials, including rubber, making it unlikely to degrade the rubber. It is best to check the manufacturer’s recommendations for the specific rubber compound used in your own application; PTFE grease may also not be as effective in extreme pressure or temperatures.

Recommended Product: Molykote 55

A silicone-based product that provides effective lubrication and sealing for rubber O-rings and seals.

It is highly reliable, offering heat and oxidation resistance across a wide service temperature range -65°C (-85°F) to +175°C(+347°F). It provides excellent oxidation resistance and reliable corrosion protection. Its wide service temperature range can be used in various industries, including aircraft, automotive, and general industrial applications.

molykote tube

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