Can different brands of engine oil be mixed together?
2 Answers
No, not only can engine oils of different brands not be mixed, but even engine oils of the same brand but different specifications cannot be mixed. Based on composition, engine oils can be divided into 3 categories. Below are the relevant details: 1. Mineral oil: (general) valid for 6 months after opening. 2. Semi-synthetic oil: (mainly composed of mineral oil with many other organic additives) (medium) valid for 6 months after opening. 3. Fully synthetic oil: (best) valid for 1 year after opening. 4. Winter oil grades are: 0W, 5W, 10W, 15W, 20W, 25W. The symbol W stands for winter, and the smaller the number before W, the lower the low-temperature viscosity, the better the low-temperature fluidity, and the lower the applicable minimum temperature. 5. Summer oil grades are: 20, 30, 40, 50. The larger the number, the higher the viscosity, and the higher the applicable maximum temperature.
Last time I ran out of gas and was desperate, so I bought a different brand of engine oil from a roadside stall to make do. After driving for a few days, the engine noise became as loud as thunder. The mechanic explained: different engine oil formulations vary greatly, and the additives can conflict, reducing lubrication effectiveness. Long-term use could wear out engine parts. I learned my lesson from that incident and now always keep a bottle of the same brand oil in my car for emergencies. Mixing oils might work in a pinch, but don’t make it a habit—saving a little money could cost you big in repairs. Veteran drivers recommend sticking to the same brand of engine oil to ensure consistent quality and protect your car longer. This way, driving feels much more reassuring.
