Is it a big deal to mix a little bit of engine oil?
2 Answers
Mixing a little bit of engine oil is not a big deal, but if too much oil is mixed, the lubrication effect on the vehicle's engine will decrease, and it may damage the engine, reducing its service life. In severe cases, it can even directly cause the engine to be scrapped. Depending on the circumstances of mixing the oil, the impact on the engine will vary. Below are some relevant details: 1. Mixing new and old oil of the same brand and specification: If the oil mixed is of the same brand and specification, it will not cause any significant impact on the engine, only affecting the working ability of the engine oil. 2. Mixing oils of the same brand but different specifications: If oils of the same brand but different specifications are mixed, it will reduce the lubrication effect of the oil, providing less effective protection for the engine. Additionally, due to the different viscosities of the oils, sludge may form, potentially clogging the engine's oil pipelines. 3. Mixing oils of different brands: The base oil additives in different brands of engine oil can vary. If oils of different brands but the same specification are mixed, the impact on the engine may be relatively minor, possibly leading to increased sludge in the engine, reducing the oil's lifespan and shortening the car's maintenance cycle. If oils of different brands and different specifications are mixed, this is the most severe scenario, not only affecting the normal operation of the engine but also potentially causing the engine to be scrapped in serious cases.
In my auto repair work, I often encounter this issue. Mixing different engine oils is generally not recommended because the additive components in various oils differ significantly, and mixing them may cause reactions that form sediments or weaken lubrication effectiveness. A small amount of mixed oil might allow the engine to run fine in the short term, but if the oil viscosities are inconsistent—for example, mixing 5W-30 with 10W-40—the protective film becomes uneven, increasing friction and wear over time, and even straining the oil pump, generating heat. My advice is that if you accidentally mix oils, check if the oil level is normal and listen to the engine sound after starting. If there are no noticeable issues, you can manage temporarily, but next time, be sure to use the same brand and specification when changing the oil—don’t cut corners for convenience. Choosing a consistent oil during regular maintenance is a wise decision, as it can extend the engine’s lifespan by two to three years or more, saving money and ensuring safety.
