There's probably not enough oil in the valve train area to worry about sucking it out.
Aside from environmental concerns, what is the advantage of a pcv system over a road draft tube?
No baffles. The amount of oil collecting on the top end should not be a concern; no need to restrict with a baffle meant to keep oil from being vacuumed out of the valve train chamber through PCV valve to the intake manifold.
Advantage of PCV systems? Environmental concerns have been the compelling reason for automobile PCV systems for 60 years. Those who will remember the wide black stripes in the middle of highway lanes, caused by millions of cars belching blowby from road draft tubes. Air was unhealthy to breathe for humans and animals. California was the first state to mandate emission control systems in all vehicles sold in the state from the mid-1960s.
