What does the 'w' in engine oil specifications stand for?

[MaggieLynn]

The letter 'w' in engine oil specifications stands for 'winter', which refers to what we commonly know as all-season engine oil. Here is a partial introduction to engine oil specifications: 1. The number before the 'w' indicates the viscosity of the oil at low temperatures. The smaller the number, the better the oil's low-temperature fluidity (cold resistance). 2. The number after the 'w' represents the kinematic viscosity standard at 100 degrees Celsius, categorized into 20, 30, 40, 50, and 60. 3. When selecting the viscosity grade of engine oil, it is necessary to consider not only the engine structure but also the local climate conditions. Each oil viscosity has a specific temperature threshold.