Can engine oils of the same grade but different brands be mixed?
2 Answers
Engine oils of the same grade but different brands cannot be mixed. The following is an explanation about engine oil: 1. Introduction: Engine oil, motor oil, or engine lubricant is a substance enhanced with additives in base oil. 2. Functions: The main functions of engine oil are to reduce friction and wear of moving parts, and to remove sludge (one of the functions of dispersants) and varnish (detergents) from the engine. It also neutralizes acids produced from fuel and lubricant oxidation (detergents), improves the sealing of piston rings, and cools the engine by carrying away heat from moving parts. 3. Composition: It mainly contains anti-wear additives, detergents, dispersants, and multi-grade oil viscosity index improvers. Engine oil is used for lubricating internal combustion engines.
With over a decade of driving experience, I often hear friends ask this question. From experience, mixing engine oils requires caution. Even if the specifications are the same, different brands have varying additive formulations, which may cause chemical reactions when mixed, leading to sediment or sludge formation and affecting lubrication efficiency. Engine internals are precise, and mixing oils can result in uneven oil films, potentially causing increased component wear and higher fuel consumption over time. Once when I was low on oil midway, I mixed a small amount of a different brand as an emergency measure—the car was fine, but I immediately replaced it with fresh oil of the same brand when I got home. My advice: don’t try to save money here. Stick to the manufacturer’s recommendation or a single brand of oil. Regularly check oil levels and follow replacement intervals to maintain stable, reliable engine performance and avoid unexpected repair costs that could end up being much higher.
