With all-season oils a pre-winter change is not mandatory, but fresh oil helps the engine. MSG Equipment explains SAE viscosity codes and oil types.
As winter approaches, many drivers ask whether they should change their engine oil. According to MSG Equipment, the all-season oils widely used today make this formally unnecessary, but since the engine works harder in the cold, fresh oil makes its job easier.
The article explains SAE viscosity markings: “W” indicates a winter grade, a number alone indicates a summer grade, a higher number means higher viscosity, and a marking with “W” between two numbers denotes an all-season oil.
If the car has been serviced according to the manufacturer’s schedule with synthetic or semi-synthetic oil, no winter problems are expected. Mineral oils, however, lose much of their lubricating ability at low temperatures.