Can Different Engine Oils Be Mixed?
2 Answers
Generally, mixing engine oils should be avoided as much as possible. More information about mixing engine oils is as follows: 1. Theoretically, oils of the same type can be mixed because they share the same base oil and can lubricate, clean, cool, seal, reduce friction, prevent rust, and protect against corrosion in the engine. 2. However, in reality, the additive compositions in oils from different manufacturers may vary completely, and even different product lines from the same brand may have different chemical compositions. When oils from any two brands are mixed, chemical reactions may occur under the high temperatures of the engine. Therefore, it is recommended not to mix oils from different brands.
As a car owner who frequently performs DIY maintenance, I genuinely don't recommend mixing motor oils. The base oil formulations and additive packages vary significantly between different brands or types of oils. Mixing them may cause abnormal chemical reactions, such as additive conflicts leading to sludge formation or foaming, which compromises lubrication effectiveness. This not only increases engine noise and fuel consumption but may also cause long-term wear and shorten engine lifespan. I once had to mix a small amount of different brand oil in an emergency oil shortage situation - while no immediate issues occurred, I completely replaced it before the next oil change. It's best to stick with the same oil product, or at least ensure compatibility between old and new oils (such as matching API ratings). If mixing is absolutely necessary, prioritize blending small amounts of the same type (synthetic with synthetic or mineral with mineral) for emergency use, then perform a full oil change ASAP. Regular maintenance using manufacturer-recommended oil remains the safest and most reliable approach.
