Dealing with the blow-by gas from reciprocating engine is a bigger challenge nowadays due to strict emission control laws and design limitations. Blow-by gas originates between the piston or piston rings and the cylinder wall and is charged with oil when it leaves the crankcase. In a closed crankcase ventilation system these blow-by gases are drawn from the crankcase into the air intake. The oil mist separator (OMS) retains a fraction of the liquid oil and returns the retained oil fraction back to the oil sump. Thus, the oil mist separator reduces oil consumption and emissions. Electrically driven cone stack separators have high separation efficiency, small differential pressure, arbitrary mounting position and low power consumption. In addition to that, the electrically driven cone stack separator has also advantageous control characteristics. Since commercial motor vehicles already have high electrical system requirements a Mechatroic concept is presented here which was developed to be maintenance-free over the lifetime of the engine. This is achieved by detailed design and choice of special materials. In this paper, the construction and application of the novel oil mist separator system for trucks are discussed in detail.