Crankcase Ventilation Systems are used to vent the combustion gases from the crankcase. Crankcase ventilation systems re-circulate the gas to the intake manifold where it is delivered to the combustion chamber for combustion. Crankcase ventilation systems incorporate a positive crankcase ventilation (PCV) valve that is typically received in the opening of a rocker cover. These systems draw combustible vapors from the oil crankcase by maintaining a slight vacuum. Crankcase vapors are discharged through an oil separator directly to atmosphere and liquid oil is returned to the crankcase. These systems provide superior oil coalescence and crankcase pressure control under the most severe conditions. They will not allow crankcase emissions to be released into the atmosphere when installed in a closed system. A crankcase ventilation system uses oil separators in order to reduce oil consumption and to reduce final emission rates of the engine. These crankcase ventilation systems are optimized by measurements of the fractional particle removal efficiency, discharge curve, pressure regulation curve and leakage.