Where's it come from?

 

The oil breather in the stock air box flows back into the air cleaner... So I'm guessing some of it could stick to the bottom of the plenum pan which would create a film. That's just my guess though. So if that's the case the stand alone breather solves that problem.

 

Mine may not be leaking yet then...just a film in the plenum...

 

That's all you should see. Just a film. And yes, it's because of the oil breather that there's a film in there.

 

Anyone ever replace the PCV with a standalone breather too?

 

Check the first post box...I linked to the pics of the intake...