What does the 'W' in motor oil grades mean?

[Dave]

The 'W' in motor oil grades stands for winter, which is the abbreviation of 'winter', indicating that this oil can be used normally in winter. Motor oil grades include 5W30, 5W40, 0W30, and 0W40. The number before the 'W' represents the oil's low-temperature flow performance. 5W means the oil can flow normally at -30 degrees Celsius, while 0W means it can flow normally at -35 degrees Celsius. The number after the 'W' indicates the oil's high-temperature viscosity, with higher numbers representing higher viscosity. Motor oil, also known as engine lubricant, serves to lubricate and reduce friction, assist in cooling, seal and prevent leaks, prevent rust and corrosion, and provide shock absorption for the engine.