[coolsvt]

The positive crankcase ventilation(PCV) system uses intake manifold vacuum to draw fresh air through the engine.Clean air is taken from either the breather cap(open system) or the air cleaner(closed system){every focus got this system the closed one}.All engines now use the closed system to prevent fumes from leaving the engine during periods of high crankcase pressure or when the engine is stopped.The air is pulled through the engine where it mixes with gases in the crankcase. The mixture of air and gases is then drawn into the intake manifold, where it is burned in the cylinders. A PCV valve controls air flow through the crankcase.

A catch can is used on a turbo car to filter the engine oil before it passes through the turbo to lubricate the bearings(journal or ball bearings) and also the oil will remove some of the heat, but the main advantage of the catch can is to reduce blow by gases and when using an intercooler it will reduce the oil formation in the core fins. B) .