Can I add a different brand of engine oil if the car is low on oil?
3 Answers
It is not advisable to add a different brand of engine oil when the car is low on oil, as engine oils from different brands should not be mixed. This is because the chemical compositions of additives in oils produced by different manufacturers may vary. When lubricants with different additive chemistries are mixed, chemical reactions between the additives may occur. If the oil level is insufficient during operation and mixing becomes unavoidable, it is recommended to use oils of similar types and the same viscosity to minimize potential negative effects. Engine oil serves to lubricate and reduce friction among internal engine components, assist in cooling, seal against leaks, and provide shock absorption. Improper lubrication due to mixing can cause significant damage to the engine. Hazards of mixing engine oils: Mixing oils can thin the oil, making it easier to be drawn into the combustion chamber and burned, resulting in blue smoke from the engine. It may also cause poor cylinder sealing, leading to black smoke. Sludge formed in the oil can reduce the cooling efficiency of the lubricant, causing the engine to overheat and increasing the risk of malfunctions. Some sludge exists as solid particles, accelerating engine wear. Other sludge may clog the oil filter and passages, impairing oil circulation and depriving the engine of proper lubrication. Mixed oils may alter sealing properties, potentially discoloring or damaging piston rods or rings. Prolonged use can lead to severe wear of these components, shortening the engine's lifespan. The viscosity of mixed oils may also change, either decreasing or increasing. Increased viscosity reduces lubrication effectiveness, potentially causing piston ring breakage. If the lubricating film is compromised, severe wear between the piston and cylinder can occur. Mixed oils may drastically alter anti-wear properties, destabilizing the lubricating film and leading to severe wear between the piston and cylinder.
I've been driving a taxi for over a decade and encountered many emergency situations with insufficient engine oil. Temporarily adding oil of another brand is acceptable in emergencies, but you must ensure the viscosity grade matches exactly – if you originally used 5W-30, don't randomly add 0W-20. I remember mixing two different brands twice before, and the engine noise became noticeably louder. The mechanic explained that mixed oils cause additive components to conflict, directly reducing cleaning performance. After adding emergency oil, immediately drive to a repair shop for a complete oil change, and don't exceed 200 kilometers, otherwise sludge deposits will accelerate engine wear. Long-term oil mixing definitely damages the engine – this isn't an area to cut corners.
When we encounter this situation during car maintenance, the first step is to check the oil dipstick to determine how much oil is missing. If it's just a temporary shortage of a small amount and you really can't find the same brand, it's acceptable to add a small quantity of synthetic oil with the same specifications. However, special attention must be paid to the differences in base oils between brands, as mixing mineral oil with full synthetic can easily lead to uneven oil film formation. Last week, a Mercedes-Benz experienced an oil pressure warning after mixing oils, and upon disassembling the engine, we found the oil pump screen was clogged. The safest approach is to purchase small bottles of the same model oil for top-up, which can be delivered the same day via e-commerce platforms nowadays—why take the risk? After adding oil, remember to schedule a full oil change within two weeks.
