Some of you guys should go to the circle races some weekend. You can look at dozens and dozens of Chevy and Ford small blocks and not see one PCV valve (it's not PVC which is a resin). It's an early anti-pollution device, nothing more. It's not about lowering pressure or preventing thinning
oil. If you're getting enough blow-by to thin your
oil or produce pressure in your crankcase you will need more than a PCV valve.
Just my $0.02.
Bob