How is the engine oil grade table classified?
2 Answers
1. Classification based on SAE viscosity grades: Engine oils are categorized by SAE viscosity grades, with 6 types for winter, 5 types for summer, and 16 types for all-season use. The 6 winter grades are 0W, 5W, 10W, 15W, 20W, and 25W. The "W" stands for Winter, and the smaller the preceding number, the better the oil's fluidity at lower temperatures. The 5 summer grades are 20, 30, 40, 50, and 60. Higher numbers indicate greater viscosity and better high-temperature protection, suitable for hotter environments. The 16 all-season grades are 5W20, 5W30, 5W40, 5W50, 10W20, 10W30, 10W40, 10W50, 15W30, 15W40, 15W50, 20W20, 20W30, 20W40, and 20W50. 2. Classification based on API quality grades: API divides engine oils into S-series (for gasoline engines) and C-series (for diesel engines). If labeled with both S and C, the oil is suitable for both gasoline and diesel engines. Each series is ordered alphabetically (A, B, C, D, E, F, etc.), with later letters indicating higher performance levels. 3. Current gasoline engine oil grades include: SA, SB, SC, SD, SE, SF, SG, SH, SJ, SL, SM, SN, and SP. Diesel engine oil grades include: CA, CB, CC, CD, CD-II, CE, CF-II, CF-4, CG-4, CH-4, and CI-4.
Having driven an old car for twenty years, I've gained a deep understanding of engine oil grade classification. It primarily follows the SAE viscosity standard, with numerical combinations like 5W-30 being common classifications. The 'W' stands for winter, and the preceding number (e.g., 5W) indicates low-temperature fluidity—the smaller the number, the smoother the cold starts. The following number (e.g., 30) represents high-temperature viscosity; a higher value offers better engine protection. Then there's the API service rating like SN or SP, where 'S' denotes gasoline engines, and later letters indicate higher grades with better cleaning and anti-wear properties. Environmental temperature significantly impacts the choice: 0W-20 offers good fluidity in frigid zones, while 15W-50's thicker consistency suits tropical climates. Once, my old Jeep developed engine knocks from using the wrong oil, costing thousands in repairs. The lesson? Always follow the vehicle manual's recommendation—don't cut corners to save small money at great cost. Synthetic oil may be pricier but lasts longer, performs reliably, and extends engine life.
