What does the SN after the engine oil represent?

[IslaLee]

SN indicates that in the "S" series, it represents gasoline engine oil and ranks in the N category. The "S" series represents gasoline engine oil, with specifications generally ranging from SA to SN (in alphabetical order, excluding SI). Each subsequent letter indicates improved performance over the previous one, with more additives included to protect the engine. Below is a related introduction to automotive engine oil. 1. Automotive engine oil grades: The "S" prefix denotes gasoline engine oil, with the following letters ranging from A, B, C, D, to N. The higher the letter, the higher the grade. Currently, the market typically offers grades above SG, including SG, SJ, SL, SM, and SN. Vehicles with lower engine technology, such as microcars or older models like the Jetta, can use SG-grade oil. SL offers the best anti-wear performance, while SM/SN usually incorporates special formulations for environmental considerations. 2. Automotive engine oil classification: Automotive engine oil is specifically classified into 4 types for summer use, 6 types for winter use, and 16 types for all-season use. Summer oils are labeled as 20, 30, 40, and 50, with higher numbers indicating greater viscosity and suitability for higher temperatures. Winter oils are labeled as 0W, 5W, 10W, 15W, 20W, and 25W, where "W" stands for Winter. The smaller the number before "W," the lower the low-temperature viscosity and the better the low-temperature fluidity, making it suitable for lower temperatures. All-season oils are labeled as 5W-20, 5W-30, 5W-40, 5W-50, 10W-20, 10W-30, 10W-40, 10W-50, 15W-20, 15W-30, 15W-40, 15W-50, 20W-20, 20W-30, 20W-40, and 20W-50. The smaller the number representing the winter part, and the larger the number representing the summer part, the higher the viscosity and the broader the applicable temperature range.