What is the SAE oil grade?
2 Answers
SAE stands for the Society of Automotive Engineers, and the SAE grade represents the viscosity grade of the oil. Here is the relevant introduction about SAE: 1. SAE specifies 11 oil viscosity grades, indicating which grade of oil should be used at specific atmospheric temperatures. Winter oils are denoted by the letter W, including 0W, 5W, 10W, 20W, and 25W. 2. The number before the W indicates the lowest temperature at which the oil is suitable. The smaller the number, the lower the temperature. Summer oils are not denoted by letters but directly by numbers, including 20, 30, 40, 50, and 60, representing the highest temperature at which the oil is suitable. 3. API stands for the American Petroleum Institute, and the API grade represents the classification of engine oil quality. It uses simple codes to describe the working capability of engine oil.
I once did thorough research on SAE standards when selecting engine oil. The number combination actually reveals secrets about temperature adaptability. For example, in 5W-30, the 'W' stands for winter, and the '5' indicates the oil's ability to flow at -30°C—the smaller the number, the better the cold resistance. The '30' represents the viscosity coefficient at the engine's high temperature of 100°C, with higher numbers indicating a stronger oil film. It's like customizing a four-season armor for your car—friends in the north should choose 0W or 5W to handle harsh winters, while those in consistently hot regions can rely on 40 viscosity for peace of mind. I remember when I last changed my old family car to 10W-40, the engine's rough noise immediately smoothed out. Nowadays, the newly introduced ultra-low viscosity 0W-20 fuel-saving formula is more suitable for hybrid models.
