For what it may be worth, I pulled the intake manifold on my LGX V6 to index the spark plugs a few months ago (and found a vacuum leak in the process).
I looked at the valves and they weren't perfectly clean, but they weren't all coked up either.
It had about 40k miles on it at the time and it consumes no measurable amounts of oil between changes.
I checked the interior of the manifold and it was completely clean and dry.
So were the throttle body and the tube that connects to the engine's air/oil separator.
There was plainly nothing there to be "caught" from the air stream.
Kudos to the LGX design team..! I was quite impressed.
I had already purchased a catch can and was planning to install it as part of the same general activity.
However once I saw the great shape the valves were in I installed it on our truck instead.
As the previous poster said, there is a very good air/oil separator just underneath the intake manifold and apparently it is doing its job nicely.
The truck on the other hand.......
