[Christ]

Single - drill a hole in the block and put a bypass filter on it.

The engine in my minivan has been known to pull so much vacuum under load that it "misplaces" the spark plug tube seals at high RPM extended periods. In this case, the PCV system of my engine is a "performance enhancer" in that it's large enough to allow the intake's vacuum to affect internal pressures.

It sucks, literally, because I get oil spray if I start revving the hell out of it though, which is obvious b/c of the smoke in the exhaust.

My old Honda also used a vacuum PCV system, employing a venturi in the intake stream to draw gasses out. Not enough vacuum to pull oil, other than vapor, though.

I can't remember what my racing tractor's engine has, but it will probably end up getting changed, since it's a splash oiling system, and I plan on running it at nearly full throttle most of the time.