What does 15w40 mean for motorcycle oil?

[MiguelMarie]

15W indicates the minimum operating temperature environment, which should not be lower than -20°C, while 40 represents the high-temperature oil viscosity. 1. 15W-40: This SAE standard viscosity value signifies that the oil is a multi-grade lubricant. The 'W' stands for WINTER, and the number preceding it denotes the pour point temperature, essentially the freezing point temperature. 2. The number following 'W' typically represents: 10W oil corresponds to a freezing point of -25°C, while 15W corresponds to -20°C. The number after 'W' indicates the kinematic viscosity of the oil at 100°C. A value of 40 means the kinematic viscosity standard at 100°C ranges between 12.5mm²/s and 16.3mm²/s.