Can Engine Oils Be Mixed?

[VonAngelo]

Engine oils contain different chemical substances, so different types of engine oils should not be mixed. Used engine oil contains many oxidation byproducts, and mixing it with new oil can accelerate oxidation, thereby reducing the oil's service life. More details are as follows: 1. The chemical compositions of engine oils produced by different manufacturers vary, and those from different brands are even more distinct. Mixing different oils may not only fail to achieve their intended lubrication performance but could also trigger adverse chemical reactions, hastening oil degradation and causing engine damage. 2. If it is absolutely necessary to add new oil, the old oil should first be completely drained before adding the new one. It is recommended to use a lubricant with relatively higher viscosity in summer and one with lower viscosity in winter.