Common rail direct injection technologies have enabled the development of very high power and torque for a given capacity of the engine. These high performance engines have very high brake mean effective pressures and peak firing pressures. These high pressures increase the blow-by gas flow in cylinder crankcase.Vehicle brake assist systems as well as some actuators on engine need the vacuum. The vacuum is generated by the vacuum pump driven by the engine cam shaft or separately as accessory drive. The air pulled for creating the vacuum gets mixed with the lubricating oil. This air mixture with the lubrication oil gets circulated in the blow by circuit. Collectively, blow-by gases and the vacuum pump oil with air carry substantial engine oil particles. These oil particles need to be separated before connecting to the air intake circuit to reduce oil consumption and to reduce exhaust emissions.Generally cyclone type oil mist separation systems are used on the automobile engines. The efficiency of cyclone type oil mist separator is better in limited range of engine speed and load when optimum velocity of blow-by is achieved. However, the efficiency reduces drastically at other speeds. Hence more oil gets carried over in the air intake system especially during transient speed and load conditions.In the present work, an innovative oil separation concept is used to get good separation efficiency level across engine speed and load transients. The concept is proven to reduce considerable oil carry over into the air intake system. This paper describes new oil separation system development. This system consists of pre-separator baffles integrated in the cylinder head cover and external oil mist separator with impact technology. This external oil mist separator has the special arrangement of impactor where in the blow-by velocity control is provided along with the media which enables good separation efficiency for varied size of oil particles at wide range of engine speed and load. Further the chosen design is verified through the series of tests.