This basic is the reason that the "
oil catchers" on the PCV side may collect small amounts of
oil (that are insignificant (note 1, 2) ) and why the other side rarely has any in it (note 3)
Note 1:
Oil catchers can gather more blow by in boosted applications which is why some blower manufacturers might include one in their kit. The legend is that this oil reduces octane and HP. The reality is that it amounts to a drop or two per tank full if that much and is in fact precisely what the PCV system is designed for.
Note 2: The presence of significant amounts of oil in the catcher under anything but redline track operation is not a solution - it is an indicator of a much bigger problem.
Note 3: Similar to #2: Some people insist on putting oil catchers on both sides. The fact is that the non-PCV side rarely shows any collection is because is is INTAKE (air flows in the vent). So, if you have oil coming out the intake side, you've got one big whoppin problem and are probably using oil measured in quarts per mile.