What is the difference between gasoline and diesel engine oil?
3 Answers
Gasoline and diesel engine oil differences: 1. Different API grades: S-prefixed oils are specifically for gasoline engines, such as SA, SB, SC, SM, SN, etc.; C-prefixed oils are specifically for diesel engines, such as CA, CB, CC, CD, CE, CF, etc. 2. Different applicability: Gasoline engine oil can only be used in gasoline engines; diesel engine oil can be used in both diesel and gasoline engines. Although both gasoline and diesel engines operate under high temperature, high pressure, high speed, and high load conditions, there are significant differences between them. During operation, the compression ratio of a diesel engine is twice that of a gasoline engine, or even more. The main components of a diesel engine endure much greater impact from high temperature and high pressure compared to a gasoline engine.
From a mechanical maintenance perspective, there are fundamental differences between gasoline engine oil and diesel engine oil, primarily due to the distinct working principles of the engines. Gasoline engines have a relatively mild combustion process with lower pressure and smaller temperature variations, so their oils contain fewer anti-wear and anti-oxidation additives, and generally have lower viscosity. Diesel engines, with their higher compression ratios, greater pressure, and more soot, require oils with more detergents to prevent carbon buildup and better shear resistance to withstand high-pressure impacts. Using the wrong oil, such as putting gasoline engine oil in a diesel vehicle, can easily lead to piston ring seizure or filter clogging, resulting in high repair costs. When selecting oil for daily use, it's best to refer to the vehicle manual: gasoline vehicles should use API oils starting with 'S', while diesel vehicles should use those starting with 'C'. Although some universal oils claim to be compatible, it's still recommended to follow the manufacturer's recommendations to ensure engine longevity and performance safety.
As an ordinary driver with ten years of experience, I personally learned that gasoline engine oil and diesel engine oil cannot be mixed. Once, I used a so-called universal oil in a diesel pickup truck, and within a few days, I noticed a lack of power and increased noise. Later, an inspection revealed severe carbon buildup. Gasoline engine oil formulations are designed for the cleanliness of gasoline combustion, with simpler additives. Diesel engines operate more roughly, requiring thicker oil that can withstand more soot and wear. Now, I always insist on buying separate oils. Diesel-specific oil may be more expensive, but it's more durable, allowing for longer intervals between oil changes and preventing small issues from becoming big problems. Just a reminder on oil change intervals: gasoline vehicles typically range from 5,000 to 10,000 kilometers, while diesel vehicles can go from 5,000 to 15,000 kilometers depending on road conditions.
