
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.

As a car enthusiast, I'm passionate about engine performance, where oil classification is key. Simply put, grading indicates oil quality—SAE denotes viscosity (e.g., 0W-20 means excellent fluidity in extreme cold, ideal for fuel-efficient cars), while API ratings like SP target wear protection in modern engines. Choosing grades depends on driving habits: low viscosity for city commuting saves fuel, high viscosity stabilizes performance for spirited driving. Testing various grades revealed SP-grade oil reduces noise and smoothens acceleration in modern cars. Remember, classifications also promote eco-friendliness—ILSAC standards emphasize fuel efficiency. When changing oil, don’t just focus on brands; check the grade label against your manual’s recommendation to boost engine longevity effortlessly.

For regular car owners, oil grading is essentially the specification label of the oil. Having driven for over a decade, grades like 5W-30 indicate the oil's viscosity at different temperatures—smaller numbers mean easier cold starts, while larger numbers ensure better engine protection in hot weather. API grades such as SN or SP denote the oil's durability and cleaning performance, with higher numbers indicating superior quality. Salespeople will advise you on the appropriate grade when purchasing a car, and it's also specified in the manual. Adjust according to seasons—use lower-numbered grades in winter. Once, I chose the wrong oil, and the engine noise increased, but switching to the correct grade resolved the issue. Don’t skimp on those few extra bucks when selecting oil—matching the right grade ensures your car runs longer and more reliably.

Working on the front lines of auto repair, oil grading is essentially a performance standard for oil. SAE viscosity grades like 10W-40 indicate the oil's flow and protection capabilities in both cold and hot conditions; API ratings such as CJ-4 are designed for diesel engines. I've seen customers use the wrong grade of oil, leading to engine carbon buildup and costing hundreds extra in repairs. Choosing the right grade depends on the vehicle's make and year—newer cars benefit from low-viscosity oils like 0W-20 for fuel efficiency, while older vehicles need higher viscosity to prevent leaks. During maintenance, I recommend checking oil quality every 5,000 km and always referring to the manual for the correct grade when changing oil—don't fall for marketing gimmicks. Oil grading is crucial for engine health and saves both time and money in maintenance.


