From what I understand...
Excess pressure built up in the crankcase (PCV gases) have a combination of gas vapors, combustion gases, and oil vapors in it. Way back when in the old days, car manufacturers use to just let this vapor exit the engine with an open hose pointed towards the ground, or let it shoot out into the atmosphere. During the pollution control years, they realized this vapor was contaminating the earth. Manufacturers decided to pump these vapors into the intake manifold, and attempt to burn these vapors off through the engine. Manufacturers just wanted to pass emission control standards, and didn't really care about the minimal loss of performance. Performance experts have determined that the attempt to re-burn these gases was detrimental to engine performance. It creates a varnish looking brownish black film that coats the intake system. AND... when it combines with the incoming fresh air, it takes up volume, but doesn't give the engine any air to burn. That causes a drop in the octane (so I'm told) and there by a drop in performance. Not a big deal for an everyday driver... but a big deal for an engine that is turbo-ed, supercharged, or custom tuned... mine is the latter.
So this is how it works...
The vapor is routed to the bottom of the canister. inside the bottom 1/2 of the catch can is a material similar to steel wool (but with thicker strands... see pic below. The hot vapor is pushed/pulled in to this canister with the pressure from the crankshaft (positive crank pressure) and pulled with the intake manifold vacuum (from the other end). When it hits the steel mesh inside the can(which is cooler), it should condensate and drip down to the bottom of the can, and collect there, The remaining air is sucked out of the top of the can, and returned to the intake manifold. The can has a drain on the bottom, and should be drained periodically. (Estimates are at oil changes)
I have not driven the car (there's still snow on the ground!), so I can't testify to how much oil it has collected, I know that I will not feel performance gains...BUT... If I get a cleaner engine, with less gunk and varnish in it... Maybe it will last a little longer. To me, it's worth the effort!
