For more than 3 decades, every automotive industry is focusing on continuous development of emission control technologies and suitable strategies. It was mainly driven by the legislation to improve or protect the environmental air quality for healthy life. Though the exhaust emission from an IC engine of an automobile is the primary and main source of pollutants, the other source such as Crankcase is also becoming a concern in recent years, while the norms becoming stringent. Hence, there is a need of regulating crankcase emissions. In a reciprocation motion of piston in an IC engine, the gases that leak past the piston rings from the combustion chamber and contain soot, particulate matter, water and oil vapor, unburned fuel and exhaust by product gases (CO, CO2, NOx, etc.) and aerosol generated from lubrication oil the entire mixture is called “blow by” gases. Crankcase emissions are bit complex mixture of combustion products and aerosol to be treated. In detail, the Crankcase Emissions from Diesel Engines and Emission Control Crankcase emissions are created during the combustion process of reciprocating engines. The primary source of crankcase emissions are combustion gases and particulate matter (PM) that escape past the piston rings and enter the crankcase. Other sources of crankcase emissions include turbocharger shaft seal leaks, valve guides and general movement of parts. These "blow-by" gases must be vented through a tube into the atmosphere to avoid pressurizing and damaging components of the engine. After mixing with oil mists in the crankcase, the gases, PM, and oil aerosols either coalesce and drop out of the vent tube onto the ground, or enter into the atmosphere as pollutants. The crankcase emissions contribute substantially to the total particulate matter (PM) emitted from an engine. Hence, the Bharat Stage VI (Euro-VI equivalent) norm legislation demands that either the combustion and crankcase emissions are combined to give a total measurement, or the crankcase gases are re-circulated back into the engine. There is a lack of understanding regarding the physical processes that generate crankcase aerosols, with a paucity of information on the size/mass concentrations of particles present in the crankcase. Crankcase emissions vary greatly depending on a number of factors. Engine rating, displacement, engine operating conditions such as load, speed and the age of the engine all influence the blow-by volumetric flow rate, mass output rate and particle size distribution. Just as important, the crankcase emissions can vary depending on the engine design especially the tolerances, materials, turbocharger, wear factors and operating conditions can impact the amount of blow-by escaping past the piston rings. This study reveals the development challenges and solutions while selecting and adopting the OCV system to a family of engines to meet the stringent tail-pipe emissions inclusive of OCV out. This development includes the design of internal parts and routing of blow-by-gases to reach OCV filter to reduce the loading at impactor / filtering element. It also covers the oil-drain locations back into the engine to work efficiently at various crankcase pressures and engine operating conditions. OCV’s internal elements such as selection of non-return-valve and oil-holding capacity to suit variety of boundary conditions and for the range of blow-by quantity and crank-case pressures. Further, the routing of external hoses and mounting the OCV at optimal location such that it meets the mechanical and function requirements in an automotive engine to work effectively at worst operating condition of the vehicles. OCV system is optimized in with engineering target on Oil-consumption and PM contribution to tail-pipe emissions which is reduced from 7% to 3% and the performance consistency is also verified in three engines.