Engine oil flows through an engine, lubricating every part. The three major functions that lubricants perform are: reducing friction, cooling, and cleaning. The main role of motor oil is to lubricate the engine parts, which are constantly subject to friction – the main cause of wear on engine parts. Lubricants reduce friction and wear, in turn reducing maintenance costs. Changing the oil not only boosts performance but not changing it reduces vehicle performance and is one of the vehicle maintenance items not to neglect.