Wolf mastertube GTS B4 10 W40 is a synthetic based engine oil advanced, especially designed for the lubrication of Petrol and Diesel 4-stroke engines of cars, including the direct injection, common rail diesel engines, HDI, CDI, etc. great fluidity at low temperature through the use of high tech components. Very low ash content. Very stable viscosity at high temperature. High resistance to ageing. Low loss through evaporation.