What does 10w-40 mean for engine oil?

[DiEva]

10w-40 for engine oil refers to: 10 represents the minimum operating temperature of the oil at -25 degrees Celsius; W stands for all-season use (Winter or Summer); 40 represents the high-temperature viscosity of the oil—the higher this number, the thicker the oil is at high temperatures. About engine oil: Engine oil, also known as motor lubricant, serves functions such as lubrication and friction reduction, auxiliary cooling, sealing against leaks, rust and corrosion prevention, and shock absorption for the engine. SAE viscosity grades for winter oils are: 0W, 5W, 10W, 15W, 20W, 25W. The symbol W stands for Winter, and the smaller the number before W, the lower the low-temperature viscosity, the better the low-temperature fluidity, and the lower the applicable minimum temperature. SAE viscosity grades for summer oils are: 20, 30, 40, 50. The larger the number, the higher the viscosity, and the higher the applicable maximum temperature.