Why You Should Never Mix Different Engine Oils in Your Diesel Generator
Sep 12, 2023
Engine oil is an essential component of any diesel generator. It lubricates the engine, reduces friction, carries away heat, cleans out tiny metal debris from wear, and also helps with sealing, damping vibrations, and preventing rust. However, some users tend to be less careful about the oil they use—mixing new oil with old, or combining different brands or viscosity grades. This can be very risky.
Mixing New Oil with Used Oil When new oil is mixed with used oil, the old oil contains oxidized contaminants that accelerate the oxidation of the new oil. This reduces the effectiveness and service life of the new oil.
Mixing Gasoline and Diesel Engine Oils Although both types of oil are made from base oils and additives, their formulations are very different. Diesel engine oil contains more additives, and even oils with the same viscosity grade are generally thicker than gasoline engine oils. Mixing them can lead to engine overheating, increased wear during cold starts, and other issues.
Mixing Different Brands of Oil Engine oils are blends of base oils, viscosity improvers, and additives. Even if two brands have the same type and viscosity, the exact composition of base oils and additives can vary. Mixing them can cause:
Oil Turbidity: Mixing oils—even with the same brand but different specifications—can cause chemical reactions that make the oil cloudy. This reduces lubrication performance and may produce acidic compounds that damage engine parts.
Abnormal Exhaust: Mixed oils may become too thin, allowing oil to enter the combustion chamber. This can cause blue or black smoke from the exhaust.
Sludge Formation: Incompatible oils can combine to form sludge. This reduces the oil’s ability to dissipate heat, leading to overheating. It can also clog filters and oil passages, preventing proper lubrication.
Increased Wear: Mixed oils may lose their anti-wear properties, damaging protective oil films. This increases wear between pistons and cylinders, and in severe cases, may cause piston ring failure.
Conclusion To avoid unnecessary damage, never mix different types, brands, or grades of engine oil. Always use the oil recommended by the generator manufacturer. If you must top off the oil in an emergency, try to use the same type and viscosity of oil that’s already in the engine. Taking these precautions will help your diesel generator run smoothly and last longer.
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