Presto

Helping a friend with some maintenance items on his 997.2. We found the whole intake manifold has a layer of engine oil inside it. His car has 80k miles 2009 C2S.
What could be the issue? Unlikely its AOS failure as that was changed about 8-10k miles ago as preventive maintenance. No excess smoke or any noticeable loss of power. Car runs fine

Presto

Hella-Buggin'

I know you changed the AOS but that's the leading culprit. Have it tested.

Petza914

You need a manometer to test the vacuum. LN Engineering sells a really nice one that I own but have never used yet or you can make your own if you search Google.
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ChicagoSpeed996

Looks completely normal. Intakes will have a little oil in there as the oil mist from the AOS condenses.

Bruce In Philly

I dunno........ the "oil" I got on my Boxster S and now my 2009 C2S is very similar to each other.... more like black soot...... not wet or at least not shiny. I never had, or found, wet oil in there. The throttle body butterfly valve would have a "varnish" on it. I would jam a rag on the end of a screwdriver and ram it up the bungy.

Peace
Bruce in Philly

docdrs