Since the 60's most PCV systems have a vacuum line to the PCV valve, and a fresh air line to the air cleaner. It all acts like a loop to purge the crankcase. An important part of the design is the baffle that is under the PCV valve, which is normally in the valve cover or valley cover. Without a baffle, oil will be drawn through the system.
I would think that plugging a PCV valve right into the freeze plug would suck up a lot of oil, hence the suggestion in the article to use a little hole, which I still don't like.
[b]The PCV valve is connected to full vacuum, not ported vacuum. The valve itself will control the flow during various vacuum levels.[/b] There are also generally two levels of PCV calibration, one higher than the other, so all PCV valves are not the same.
The crankcase needs to breath, or you will end up with every gasket in the engine seeping oil.
