What is the difference between diesel engine oil and gasoline engine oil?
2 Answers
The differences between diesel engine oil and gasoline engine oil are as follows: 1. Different fuel economy grades: According to the ACEA European Lubricant Classification Standard, the latest 2007 version classifies them into three series. They are: A/B series: Engine oil for gasoline and light-duty diesel engines. C series: Catalyst-compatible engine oil. E series: Heavy-duty diesel engine oil. 2. The compression ratio of a diesel engine is more than twice that of a gasoline engine, and its main components endure much higher temperatures, pressures, and impacts than those in a gasoline engine. Therefore, some parts are made of different materials. 3. Diesel fuel contains more sulfur than gasoline. This harmful substance forms sulfuric or sulfurous acid during combustion, which, along with high-temperature and high-pressure exhaust gases, enters the oil pan, accelerating the oxidation and degradation of the oil. Thus, diesel engine oil formulations require more antioxidant additives and additives that make the oil more alkaline. Additional Information: 1. There are two main criteria for selecting the quality grade of diesel engine oil. One is based on the combined mechanical and thermal load of the automobile engine, expressed as a strengthening coefficient; the other is based on the severity of the engine's operating conditions. 2. The selection of the appropriate performance grade (quality grade) of gasoline engine oil is based on the severity of the engine's operating conditions, the additional devices in the intake and exhaust systems of imported vehicles, and the production year. Generally, a higher-quality grade can replace a lower-quality grade, but a lower-quality grade should never replace a higher-quality grade, as this could lead to engine failure or even damage.
I've worked in an auto repair shop for ten years, and whenever someone asks about the difference between diesel and gasoline engine oils, I always emphasize the additive composition. Diesel engines have higher compression ratios, so the oil must contain more antioxidants and detergents/dispersants because diesel combustion produces large amounts of carbon deposits and acidic substances. Gasoline engines operate at higher RPMs, so their oils focus more on low-temperature fluidity and reducing sludge formation. The API standards are also different - S-grade ratings are for gasoline engines only, while C-grade is for diesel vehicles. Using the wrong oil can easily clog the oil filter, and in severe cases, it may even cause scoring on the piston rings.
