4. Lubrication system
For engines of the S-class use of all-weather oils is recommended. They are produced on liquid seasonal oil (for example, 15W) and therefore it is optional to change them seasonally (summer / winter). By means of so-called thickeners oil is stabilized in a hot state."W" in the designation SAE means that oil is suitable for use in the winter.
All-weather oils which, along with other additives, include components for reduction of coefficient of friction in the engine are called very fluid. A basis of very fluid oil is so-called synthetic oil. Upon purchase of very fluid oils it is necessary to pay attention to that it was authorized for use by Mercedes (designation on a container).
Neither to fuel, nor it is impossible to add additional lubricant resources of any kind to lubricant oils.