Can You Mix Different Engine Oils in a Car?
1 Answers
It is not advisable to mix different engine oils in a car. The reasons why engine oils should not be mixed include reduced performance when new and old oils are mixed, and the formation of turbidity when different oils are combined. Below are the detailed explanations: Mixing new and old oils reduces performance: New and old engine oils should not be mixed. Old oil contains a large amount of oxidative substances. When new oil is mixed with old oil, the oxidation rate of the new oil increases, thereby reducing its effectiveness and service life. Tests have shown that when the old oil in a diesel engine is completely replaced with new oil, the oil's service life can reach up to 1,500 hours. However, if half of the new oil is mixed with half of the old oil, the service life of the oil is reduced to only 200 hours, significantly shortening its usability. Mixing different oils causes turbidity: Engine oils of different brands and grades should not be mixed. Since the chemical additives in oils of different brands and grades vary, these additives can sometimes react with each other, reducing lubrication effectiveness and producing acidic or alkaline compounds that accelerate the corrosion of engine components. Most modern engine oils use sulfonates as dispersant detergents, while some oils use salicylates instead. Salicylates are incompatible with the sulfonates used in other lubricants. If these two types of lubricants are mixed, phenomena such as layering, turbidity, and deterioration of cleaning ability may occur.
