How is engine oil quality graded?
2 Answers
Engine oil quality grading: The API grade represents the quality level of engine oil. API engine oils are divided into two categories: the "S" series denotes oils for gasoline engines, while the "C" series denotes oils for diesel engines. The oil grade levels are classified as SA, SB, SC, SD, SE, SF, SG, SH, SJ, SL, SM, and SN, with later letters indicating progressively higher grades. SN grade currently represents the highest quality level. Engine oil, also known as engine lubricant, serves multiple functions including lubrication and wear reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion protection, as well as shock absorption. It is often referred to as the "blood" of automobiles.
Engine oil classification is primarily determined by two major systems: SAE and API. SAE is responsible for viscosity grading, such as 5W-30. The 'W' stands for winter suitability, with a smaller number indicating better low-temperature fluidity. The following number represents high-temperature viscosity, where a larger number indicates stronger protection at high temperatures. API, on the other hand, grades performance, such as SP or SN. The later the letter in the alphabet, the higher the oil quality, with better cleaning ability and anti-wear properties. There is also the ILSAC standard, like GF-6A, which is suitable for energy-efficient models. When choosing engine oil, refer to the car's manual for recommendations. My experience is to use oil with higher high-temperature viscosity in summer and oil with better low-temperature fluidity in winter. Never use lower-grade oil, as it can lead to accelerated engine carbon buildup and wear. Regular oil changes are crucial, typically every 5,000 to 10,000 kilometers. Remember, good engine oil can make your car run more fuel-efficiently and quietly.
