Can 5w40 engine oils of different brands be mixed?
3 Answers
5w40 engine oils of different brands cannot be mixed. It is prohibited to mix lubricants from different brands or of different grades, as the production standards of lubricants from different manufacturers are inconsistent. Mixing them may cause damage to the engine. Here is some information about engine oil: 1. Composition of engine oil: Engine oil is the lubricant used in engines, consisting of base oil and additives. 2. Density and functions of engine oil: The density of engine oil is approximately 0.91×10³ (kg/m³). It serves to lubricate and reduce wear, assist in cooling, seal against leaks, prevent rust and corrosion, and provide shock absorption for the engine.
As a veteran driver with 20 years of experience, I once tried mixing 5w40 engine oils from different brands, which resulted in increased engine noise and slightly higher fuel consumption. Although the viscosity grades were the same, each brand uses different base oils and additive formulations. Mixing them can easily trigger chemical reactions, leading to sediment formation or reduced lubrication effectiveness. On one emergency occasion, I used half a bottle of another brand's oil and promptly changed to fresh oil after driving about a thousand kilometers. I usually recommend car owners stick to one brand consistently, regularly checking oil levels and color. Engine oil is the heart-protecting medicine for your engine - don't cut corners by mixing randomly, or you'll pay hefty repair bills later.
I've worked in the maintenance shop for many years doing car servicing, and I really don't recommend mixing different brands of 5w40 oil. Although the oil specifications are all 5w40, the antioxidants, detergents, and other additives vary greatly between manufacturers. Random mixing can lead to clogged filters or corroded parts. When customers ask, I always emphasize the importance of consistency; mixing a small amount in an emergency isn't a big issue, but it should be replaced after running 300-500 kilometers. Also, pay attention to whether the oil certification standards are compatible, such as API or ACE standards. When changing, ensure all the old oil is completely drained, and don't leave any residue when adding new oil.
