disclosed are lubricating compositions and base oils for motor vehicles , specifically for engines , gearboxes , or vehicle axle assemblies . the lubricating composition contains an oil - soluble polymer that is a specific polyalkyl glycol or a specific polyalkylene glycol . also described is use of the lubricating composition for reducing fuel consumption in a vehicle provided with an engine , an axle assembly , or a gearbox that are lubricated using the lubricating composition or the specific pag .