Can engine oils of different brands be mixed together?

[DelaneyFitz]

Engine oils of different brands should not be mixed together. Here are the relevant explanations: 1. Mixing engine oils may lead to the formation of flocculent substances, increased viscosity, and other issues. Engine oils from different brands may even undergo chemical reactions. 2. The additive components in engine oils from different manufacturers are completely different. The chemical compositions of various additives can vary significantly, not only between different brands but also between different product lines of the same brand. There is no guarantee that any two brands of engine oil will not react chemically under the high temperatures in an engine. However, it is certain that some combinations of engine oils will produce adverse reactions, such as the formation of flocculent substances or increased viscosity. 3. During maintenance, when changing to a different brand of engine oil, it is essential to drain the old oil from the engine as thoroughly as possible. Although it is impossible to ensure 100% removal, the cleaner the better. For gravity draining, it is best to let the oil drain for more than two hours.