Can Different Brands of Motor Oil Be Mixed?
2 Answers
Different brands of motor oil can be mixed, but it is not recommended. Many car owners have tried mixing two types of motor oil. It is important to note that when mixing oils, the viscosity grade and performance level must be the same, for example, both should be fully synthetic 5W30 or fully synthetic 5W40. Motor oil serves multiple functions in an engine, including lubrication to reduce friction, assisting in cooling, sealing to prevent leaks, protecting against rust and corrosion, and acting as a shock absorber. Motor oil, also known as engine oil or engine lubricant, is a substance enhanced with additives in a base oil, primarily containing anti-wear additives, detergents, dispersants, and viscosity index improvers for multi-grade oils. Motor oil is used for lubricating internal combustion engines.
I've been repairing cars for over 20 years, and mixing engine oils is really not a good idea. Different brands or types of oils, such as mineral oil and synthetic oil, may have additives that conflict with each other. Mixing them can easily form deposits or damage lubrication performance. Once, a customer mixed two types of oil in an emergency, and soon after, the engine started making unusual noises. Upon disassembly, we found the oil passages clogged with impurities, and unstable oil film accelerated component wear. The core function of engine oil is to protect the engine from excessive friction and aid in cooling. Mixing oils can alter viscosity and compromise overall protection. I've seen too many similar cases—minor issues like increased fuel consumption or severe ones like engine failure. I always advise car owners to completely drain the old oil during each oil change and use fresh oil of the same specification. Don't take big risks to save a little effort—in the long run, repair costs can far exceed the price of oil. Safe driving starts with careful oil changes.
