Oil seals are commonly used in engines, gearboxes, and other rotating machinery to prevent the leakage of oil from shafts and bearings. They are typically made from rubber or elastomeric materials that are resistant to oil and heat. The seal is installed in a housing or bore that is larger than the shaft, and it is pressed against the shaft to create a tight seal.

Polytetrafluoroethylene 
Chemical resistant 
Low coefficient of friction poor elastic properties not wear resistant if used by dynamic applications