Let’s begin to understand. The number preceding the W is the dynamic viscosity range of the oil. In other words, how much energy is necessary to move the oil at cold temperatures? The W stands for winter and means that the oil has a cold temperature rating. This number could be a 5, 10, 15, 20 or 25. This rating is crucial in cold weather because it indicates how easily oil can be pumped into a cold engine and begin to provide lubrication. The lower this number is, the easier the oil flows at cold temperatures.

The number succeeding the W is the kinematic viscosity and represents how easily the oil pours at 212 degrees Fahrenheit. These numbers can be 8, 12, 16, 20, 30, 40, 50 and 60. The higher the number the slower the oil pours. This number gives guidance as to how thick an oil is at the approximate operating temperature of an engine.The 8, 12 and 16 are fairly new kinematic grades. Toyota and Honda are specifying SAE 0W16 for some of the engines used in their 2018 models.