What does 5W40 SN grade mean?
2 Answers
SN is the grade of the engine oil, 5W represents the low-temperature fluidity of the oil. The smaller the number in front, the better the low-temperature fluidity of the oil. 40 indicates the viscosity of the oil after the engine is operating normally, and the higher the number, the higher the viscosity. More details are as follows: 1. Grade: The grade after the oil classification indicates its viscosity specification. For example, in "15W-40, 5W-40," "W" stands for Winter. The smaller the number before it, the better the low-temperature fluidity of the oil, representing a lower usable environmental temperature and better engine protection during cold starts. For example, 5W represents resistance to external low temperatures of -30°C, while 20W is resistant to -15°C. 2. Oil classification: Oil classification is represented by a combination of two letters. The "S" series represents oil for gasoline engines, with general specifications ranging from SA to SN (in alphabetical order, but without SI). Each subsequent letter indicates better performance than the previous one, with more additives in the oil to protect the engine.
5W40 SN grade refers to a specification of automotive engine oil. I think many people don't understand that it actually consists of two parts. First, let's talk about 5W40. These numbers represent viscosity grades. Having driven many cars, I can explain that 5W refers to low-temperature fluidity - for example during winter startups, a smaller number indicates thinner, more freely flowing oil that won't jam the engine. The 40 indicates viscosity at high temperatures, where a larger number means the oil maintains thicker protection for engine components during hot weather driving. Then there's the SN grade, which comes from API (American Petroleum Institute) standards designed for modern gasoline vehicles. When I change oil, I always look for this - SN signifies higher cleanliness and environmental performance, reducing carbon deposits and protecting catalytic converters. This type of oil works well for all-season driving, especially for urban commuting, but be careful not to buy counterfeit products. Regular oil dipstick checks are crucial, as wrong choices can accelerate engine wear.
