What does oil a1b1 mean?

[MacLilliana]

Oil a1b1 is the inspection and certification standard for automotive lubricants established by the European automobile manufacturing industry. a1 represents the quality grade for gasoline engine lubricants, while b1 denotes the quality grade for light diesel engine lubricants, indicating low viscosity for economical fuel consumption, equivalent to API SJ and CJ levels. The functions of engine oil are: 1. As a lubricant, it reduces friction and wear between moving parts; 2. As a coolant, it absorbs heat generated in the engine combustion chamber and piston crowns, cooling the engine and protecting it from overheating; 3. As a sealant, it fills the gaps between piston rings and cylinder liners to prevent combustion pressure leakage.