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. Use silicone grease when you need a rubber- and plastic-friendly option, PTFE when chemical inertness is the priority, and petroleum-based grease only when the seal manufacturer confirms compatibility.
