What Does 10w40 Engine Oil Represent?

[AnaLee]

Engine oil labeled 10w-40 indicates that the number 10 represents the minimum applicable temperature of the oil, which is -25 degrees Celsius; W stands for all-season use in both summer and winter; 40 represents the high-temperature viscosity of the oil, with higher numbers indicating thicker oil at high temperatures. Below is relevant information: 1. Engine oil, also known as motor lubricant, serves to lubricate and reduce friction in the engine, assist in cooling, seal against leaks, prevent rust and corrosion, and provide shock absorption. 2. The 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. 3. The SAE viscosity grades for summer oils are: 20, 30, 40, 50. The higher the number, the greater the viscosity, and the higher the applicable maximum temperature.