What is the gasoline engine oil grade chart?

[GeorgeFitz]

Automotive engine oil grades range from SA to SN, with each increasing letter indicating a higher quality level. The functions of engine oil include the following three points: 1. Lubrication: There is rapid relative sliding between the piston and cylinder, as well as between the main shaft and bearing shells. To prevent excessive wear of parts, an oil film needs to be established between the two sliding surfaces. 2. Auxiliary cooling: Engine oil has a relatively low specific heat value and is located inside the engine, so it does not inherently have a cooling function. However, due to the heat energy generated by fuel combustion in the engine, during operation, engine oil can carry heat back to the oil tank and then dissipate it into the air, assisting the radiator in cooling the engine. The actual cooling is performed by the water outside the engine casing. 3. Anti-wear: Adding lubricants can reduce the friction coefficient, thereby decreasing frictional resistance, saving energy consumption, and reducing wear. Lubricants between friction surfaces can minimize wear caused by abrasive particles, surface fatigue, etc.