- The primary function of an oil seal is to prevent the loss of oil from the sealed system while allowing the free movement of the shaft or other rotating components. This is achieved through the use of a flexible material that conforms to the surface of the shaft and creates a tight seal. The material used in oil seals is typically a synthetic rubber or a thermoplastic, which provides excellent resistance to heat, oil, and other chemicals commonly found in machinery environments.
Seals perform much better and longer when they are continuously lubricated with an oil that has the correct viscosity for the application and that is compatible with the seal lip elastomer material. The consideration of seal incompatibility, particularly with certain additives and some synthetic lubricants, should not be ignored, but unfortunately very often is.
Lubricants applied between moving and stationary elements of mechanical equipment help to prevent damage. But when the equipment are under high pressure, the lubricants tend to escape, hence the need for oil seals to prevent the clashing of dry parts. Practically all mechanical equipment, including car engines, assembly machines, and PTFE machined parts use these oil seals to prevent harmful interaction that can result in damaged parts.

Some aspects to consider when selecting this component are: