I am considering installing an air-oil separator in my 172H (Cont
O-300d). I have spoken with Airwolf who say theirs will work well and
is ALMOST STC'd but they "will provide the required paperwork to make
it legal until the STC comes thru" (whatever that means).
I also spoke with Aircraft Spruce who say the M-20 is the one for my
plane and it is already approved.
Airwolf is $495 M-20 is $360

Any suggestions/PIREPS/considerations/anecdotes appreciated.