Can Different Brands of Motor Oil Be Mixed?

[DeSadie]

Motor oils of different brands can be mixed, but it is not recommended. Below is relevant information about mixing motor oils. Precautions for Mixing: When mixing several types of motor oil, the oil grade and classification must be consistent, such as both being fully synthetic 5W30 or fully synthetic 5W40. Negative Effects of Random Mixing: Turbidity: Most modern motor oils use sulfonates as dispersants and detergents, while some use salicylates. These two types are not compatible, and mixing them can lead to phenomena like layering, turbidity, and reduced cleaning performance. Abnormal Exhaust Emissions: Mixing different brands of motor oil may cause abnormal exhaust smoke, such as black or blue smoke. Mixed oil may become diluted, making it easier for the oil to enter the combustion chamber and burn, resulting in blue smoke from the exhaust pipe. Mixed oil may also compromise cylinder sealing, leading to black smoke emissions.