Silicone grease is commonly used for lubricating & preserving rubber parts, such as O-rings. Additionally silicone grease does not swell or soften the rubber, which can be a problem with hydrocarbon-based grease. It functions well as a corrosion-inhibitor & lubricant for purposes that require a thicker lubricant. Thermal grease often consists of a silicone grease base along with added thermally conductive fillers. It is used for heat transfer abilities rather than friction reduction.