How to Classify Engine Oil Grades?

[KinsleyMarie]

Engine oil grades are typically classified by two methods: viscosity classification and oil quality classification. I. SAE Viscosity Classification: 1. High-temperature type for summer: 20, 30, 40, 50. The larger the number, the higher the viscosity, indicating suitability for higher maximum temperatures. 2. Low-temperature type for winter: 0W, 5W, 10W, 15W, 20W, 25W. The letter W stands for Winter, and the smaller the number before W, the lower the low-temperature viscosity and better low-temperature fluidity, indicating suitability for lower minimum temperatures. 3. All-season type for both winter and summer: 5W-20, 5W-30, 5W-40, 5W-50, 10W-20, 10W-30, 10W-40, 10W-50, etc. The smaller the number before W, the lower the minimum temperature the oil can withstand, and the larger the number after the hyphen, the higher the maximum temperature the oil can withstand. II. API Engine Oil Quality Classification: 1. Oils starting with S: SA, SB, SC, SD, SE, SF, SG, SH, SJ, SL, SM, SN. These oils start with S, and the letters range from A to N. Each subsequent letter represents a higher grade than the previous one. For example, SN is a higher grade than SM. 2. Oils starting with C: CA, CB, CC, CD, CE, CF. These are general-purpose diesel engine oils, and their letter grades are similar to S-grade oils. The later the letter in the alphabet, the higher the oil grade.