How to Distinguish Engine Oil Viscosity Grades?
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Engine oil viscosity grades are distinguished as follows: The viscosity grade of the oil is indicated on the oil bottle. 'SAE' represents the viscosity grade of the oil. The number before 'W' indicates the winter viscosity—the smaller the number, the lower the viscosity. The number after 'W' indicates the summer viscosity—the larger the number, the higher the viscosity. The functions of engine oil include: 1. Lubricating between pistons and cylinders, and between main shafts and bearings; 2. Carrying heat back to the oil tank and dissipating it into the air to help the radiator cool the engine; 3. Transporting carbon deposits, sludge, and worn metal particles from engine components back to the oil tank through circulation, cleaning contaminants from the working surfaces of parts; 4. Forming a seal between piston rings and pistons to reduce gas leakage and prevent external contaminants from entering; 5. Providing rust and corrosion protection; 6. Cushioning the load on pistons, piston skirts, connecting rods, and crankshaft bearings; 7. Reducing the coefficient of friction.