What does it mean when....

[flmont]

Air blows out of oil fill tube (as it runs) on 01 Boxster S. I mean a lot of air, bad oil separator ??

[ottobon100]

Typically with a failing AOS you would get suction at the oil fill tube. I got this response from another forum member after posing your question to another forum: "Likely due to combustion pressure leaking past the piston rings, if not a plugged crankcase ventilation system AOS. A compression check (dry and wet) is recommended." Another member posted: "A positive pressure at the oil filler tube would seem indicate a high pressure in the crankcase." Hope this helps.

[ottobon100]

https://forums.pelicanparts.com/boxster-cayman-forum/999842-my-aos-failure-symptoms.html

[Dmitry at Pelican Parts]

Some more info in addition to the ottobon100 provided:

https://www.pelicanparts.com/techarticles/Boxster_Tech/09-ENGINE-Air_Oil_Separator/09-ENGINE-Air_Oil_Separator.htm