What is the classification of automotive engine oil?
2 Answers
Engine oil, also known as engine lubricant, is composed of base oil and additives. The base oil is the main component of lubricating oil, determining its fundamental properties, while additives compensate for and improve the deficiencies in the performance of the base oil. The classification of automotive engine oil is as follows: 1. AB series: Gasoline and light-duty diesel engine oils. 2. C series: Catalyst-compatible engine oils. 3. E series: Heavy-duty diesel engine oils. The functions of engine oil are as follows: 1. Cooling: Cools and reduces temperature. 2. Sealing: Seals and prevents leaks. 3. Cleaning: Cleans and maintains cleanliness. 4. Buffering: Absorbs shocks and cushions. 5. Lubrication: Lubricates to reduce wear.
I've worked in auto repair shops for decades and seen too many people suffer from not understanding oil classification. Oil grades are primarily based on international standards, such as SAE viscosity and API ratings. SAE grades like 5W-30 mean the '5W' indicates good oil flow at low winter temperatures, while '30' represents strong protection at high temperatures. API grades like SN indicate higher numbers offer better engine protection. These classifications aren't arbitrary—they're determined through engine design testing. I remember one time when a friend used W20 oil for northern winter driving; the oil was too thick to start the engine until he switched to the proper grade. After all these years working with cars, my advice is: always check your owner's manual recommendations—don't cheap out and buy randomly. Even a slight mismatch in grade increases engine wear, leading to costly repairs. Regularly checking oil condition during maintenance extends your car's life, especially critical for older models when selecting the right grade. In short, proper grading matches your vehicle's needs—never underestimate its importance.
