Internal combustion engines have a variety of moving metal parts that move very quickly. These parts would become damaged by friction if not properly lubricated. The engine oil provides this necessary lubrication. However, oil does not last forever. Both the heat of the engine and the passing of time will cause oil to begin to break down, becoming less effective. It will no longer be able to provide the same level of protection against friction damage and may also leave sludge deposits in your engine. To prevent old oil from damaging your vehicle, you should have the oil changed regularly. If your vehicle is high in mileage consider speaking to one our service advisors about switching to high-mileage oil.