The catch can will stop your engine from burning almost all of that oily gunk. As a result, the throttle body, valves, and cylinder where it is burned will stay much cleaner and you will not lose performance as your engine ages.
They are especially important if you are using synthetic oil. Oils such as Mobil 1 do not burn very well, compared to DINO oils.
Last edited by Cuda340; 04-11-2010 at 04:53 PM.