Why do I need to change the oil?

Article from Castrol Archives.

Oil is constantly battling against the stresses inside the engine. These can be thermal, at the hottest parts of the engine; chemical in resisting the acids, particulates and water that are made during combustion; or physical, in resisting the tremendous forces and speeds in modern engines.

Each manufacturer balances these stresses against the quality of oil they recommend, and advises an appropriate oil drain interval to give the right protection and performance. The manufacturer’s drain interval can be found in your vehicle handbook. Some modern cars will also indicate when an oil change is due on the instrument cluster.

When the oil is changed, it is prudent to change the filter at the same time. The oil filter collects all the dirt and combustion by-products which the oil catches on its journey around the engine. Fitting a fresh filter with new oil will keep your engine in the best condition for maximum performance.