Selection of quality grades: Currently, there are eight quality grades of gasoline engine oil in the Chinese market, including SC, SD, SE, SF, SG, SH, SJ, and SL. In order to ensure the reliability and economy of engine operation, appropriate quality grades of engine oil are selected based on the structural characteristics, operation, and road conditions of the engine.

Equivalent to gasoline engines produced before the mid-1960s in the United States, with a compression ratio of less than 7, SC grade oil can be used, such as Dongfeng 140, GAC 69, and Toyota SenseTime RY16L.

Gasoline engines manufactured in the United States after the late 1960s were equipped with a positive pressure crankcase exhaust system (PCV) with a compression ratio of approximately 7, requiring the use of SD grade oil, such as Jiefang CA141, modified Dongfeng, Isuzu dual seat ELF, Mitsubishi Xiaoka L200, etc.

Equivalent to gasoline engines manufactured in the United States after the late 1970s, with the addition of a waste gas circulation device (EGR) and an increase in compression ratio to 8-9, SE grade oil should be used, such as Tianjin Dafa, Beijing Jeep, Mazda, Fiat, Toyota Crown, etc.

Equivalent to gasoline engines manufactured in the mid to late 1980s in the United States, ordinary carburetor engines equipped with exhaust catalytic converters require the use of SF grade oil. Such as Santana, Audi, Jetta, Nissan, etc.

By the early 1990s, exhaust emission standards had become increasingly stringent, and requirements were put forward to extend oil change periods and improve energy efficiency. In the early 1990s, gasoline engines produced in the United States, such as Buick, Cadillac, Chrysler, and China's Citroen Fukang, were required to use SG grade oil.

According to the requirements of the original engine manufacturer, the reliability of the oil has been further improved to prevent damage to the vehicle caused by oil quality, and the oil change period has been extended. Electric fuel injection vehicles equipped with three-way catalytic conversion devices require the use of oil with a quality grade of SH or higher. For example, gasoline powered vehicles manufactured in the United States after 1993, luxury sedans such as Lincoln, Cadillac, and Buick, as well as Audi A6, Bora, and Xiali 2000 in China.

New cars produced in China after 2002 will require the use of SJ grade oil with better actual performance, while American car manufacturers require the use of higher-level SL oil. It is worth emphasizing that due to the requirements of the engine design itself, some new cars must use low viscosity engine oil, such as Shanghai General Motors requiring the use of 5W30SL/GF-3, Bluebird, and Guangben requiring the use of 5W30SJ. In this case, special attention should be paid to recommending engine oil to users, and viscosity levels should not be determined solely based on environmental temperature.