Can engine oils of the same brand but different grades be mixed?

[DiArcher]

Mixing small amounts of engine oils of the same brand but different grades is generally safe. However, mixing large quantities cannot be guaranteed. Below is additional information: Mixing engine oils of the same brand but different grades: Since the oils are from the same brand, compatibility is usually ensured, whether it's the base oil or additives. However, the performance after mixing is uncertain, and the characteristics of both grades may not be fully realized. Mixing engine oils of different brands but the same grade: For oils of different brands but the same grade, the base oils may differ, and the additives are likely to be different. In such cases, the probability of issues is relatively higher. Additives from different manufacturers vary; for example, most engine oils use sulfonates as dispersant detergents, while some use salicylates. These two substances are incompatible and may cause separation or cloudiness when mixed, affecting performance.