Without its precious oil, your engine would rapidly over heat and seize up, resulting in a costly engine replacement. Correctly formulated, clean oil is vital to the longevity of your engine, reducing wear on the moving components and keeping your engine running like new for as long as possible. If your car is regularly serviced, then the correct oil changes should have been observed in the service schedule. If you’re not getting your car regularly serviced or have recently bought a car with no service history, the one job you really need to take care of is the oil change.
As a rule of thumb, oil should be changed every 5000 miles. Oil filters are usually quite cheap so it’s a good idea to change this at the same time. Over time deposits like carbon build up in the oil and cause it to become sludgy and the additives in the oil will break down, changing its characteristics. Always use the vehicle manufactures recommended type of oil, though you may want to use specially formulated oil for high mileage vehicles if appropriate.