The purpose of oil or lubricants is to reduce the friction between two metal surfaces. It does this by sticking to each surface and forming a thin film that keeps the metal components apart. The parts effectively ‘float’ on a thin film of oil or lubricant which stops metal to metal contact, reduces friction, heat and wear. The quality and performance of oil is a measure of its ability to perform these functions over a long period of time thereby increasing the reliability and performance of the engine components being lubricated.