Can engine oils of the same grade but different brands be mixed?

[MacBrantley]

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.

[LincolnDella]

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.

[KeeganDella]

I used to mix engine oils for convenience, thinking the same grade should be fine, but after that incident, the engine noise increased. Upon checking, it might be due to additive conflicts weakening protection. Different oil brands have varying formulations with hidden risks, and mixing them can easily lead to unstable oil quality and insufficient lubrication, accelerating wear. It's acceptable to top up temporarily in emergencies, like running low on oil during a highway trip, but make sure to refill with the same product as soon as possible. Long-term mixing is definitely a bad habit, increasing the risk of oil filter clogging and leading to staggering repair costs. Develop the habit of checking maintenance records and stick to the original recommended oil for optimal performance, durability, and peace of mind—it saves money in the long run.

[MacCaroline]

From a cost-saving perspective, mixing engine oils might seem economical, but it actually carries high risks. Oils of the same grade share similar base performance, but each brand has its unique additive system. Mixing them could reduce cleaning efficiency or anti-wear properties. Temporary mixing is acceptable in emergencies, but it shouldn't become a regular practice. Long-term mixing may lead to impurity buildup, affecting engine efficiency and lifespan. The repair costs could far exceed the savings on oil. It's recommended to purchase sufficient quantities of the same brand oil for backup storage, avoiding potential damage caused by frequent mixing.

[VanLena]

As a safety-conscious person like me, I firmly oppose mixing engine oils. Engine protection relies on the consistency of oil composition. Mixing different brands can cause additive conflicts, potentially forming sludge that clogs oil passages or accelerates corrosion, leading to power loss or even engine failure. If dealerships detect mixed oil traces during the warranty period, they may deny claims, resulting in significant losses. Once I saw a neighbor's car require major cylinder overhaul due to mixed oil usage at great cost. It's best to strictly follow the manual and use specified brands and models to ensure safe and reliable driving.