I was using a convectional PVC system. This type of system does nothing to create vac in the crankcase. I put a MAP sensor on the crankcase and I was getting positive pressure in the crankcase with a conventional PCV system. And I was always getting oil leaks. No mater how many times I sealed it up, it would always leak oil. I had to keep mats under it to soak up all the oil.
So, this is what I did to fix the problem. I got a fixed orifice PCV valve. I then put a one way check valve in the line between the PCV and the manifold so it could only pull vac in the direction of the manifold. I then put a restriction in the vent line going from the other valve cover to the breather vent in the TB. I then played with the sizes of the PVC valve and the restriction in the vent line until I got about 7" of vac in the crankcase at idle. Then I T'ed off the vent line and connected an electric smog pump. And then I put an one way check valve in this pump line. As I am driving around the crankcase gets it's vac from manifold vac, and when crankcase vac drops below 3.5" or I go to WOT the ECU turns the smog pump turns on and keeps the crankcase vac around 5" of vac. Since doing this all my oil leaks have stopped and the mats are now gone. And as a bonus the vac in the crankcase helps ring seal.