Engine oil imparts film on all moving parts in your engine. Over time dirt, abraded metal, and the residue of combustion get into the engine oil which then makes the engine oil more thicker and less filmy. Thus causing the performance of your engine to become impaired, raising your fuel consumption and causing engine damage. Regular maintenance of your engine’s oil is a must. Looking in your owners manual will give you a recommended mileage on which to have your vehicles engine oil serviced. If you do not reach the recommended mileage then having your oil changed once a year is recommended.