wrote

Unless that engine is really tight (pretty much zero ring
leakage) he'll end up with backpressure in the crankcase and will blow
the front crank seal out, losing oil at a good clip

I agree.

How come airplane engines don't have PCV valves, plumbed back into the intake
manifold, like cars? You could even use an oil separator, before the gas enters
the manifold, if too much oil was worried to be a problem.

An arrangement like that would solve the oily discharge on the belly, I would
think.

Might even keep the intake valves lubricated a little bit! g

I wonder what the answer is, and why that solution would be a problem. I'm sure
it has been tried, since it seems there is truly nothing new under the sun, when
it comes to airplanes.
--
Jim in NC