Do we need a PCV System?

[Aussie Challenger]

  The whole idea of a PCV system is to stop oil and oil vapor being released into the atmosphere, very early engines had just a "walking stick" type of tube exiting onto the roadway. Racing motors have the catch can arrangement to stop oil being dropped onto the track as the fumes would only foul spark plugs if directed back into the motor to be burnt.
  I like the can displayed by invoilet but it must be remembered that if the excess pressure builds up inside the crankcase or R/C seals will blow giving major oil leakage problems.   

[cudabob496]

PCV systems removes ring blow-by contaiminants that would get into your oil.  20% of which
are water I believe.