Not changing your oil on a regular basis can significantly reduce the level of protection provided against engine wear. Engine oil acts as a reservoir for all kinds of by-products that form when the fuel burns, including soot, sludge, water and acidic material, as well as unburned and partially burned fuel. At the same time, the stress placed on the oil during engine operation gradually depletes the components that determine the oil’s performance. Refreshing the oil on a regular basis ensures that the right balance of components is present in the oil.
It also removes waste materials that might otherwise result in increased deposit formation, corrosion of metal components and increased wear."