I am trying to diagnose any possible issue.
i have done the tea kettle test no bounce just sitting there but when i laid under the truck and covered breather the other guy watching over the top said the cap moved maybe a 1/4 of an inch
i have a pretty bad oil leak as well trying to track it down day by day today i think i have noticed a good amount may be coming from the blowby tube.
and the other main leak looks to be coming from behind the PCM. these 2 make me concerned of crankcase pressure causing oil leaks.
but the truck runs very strong got 24 mpg going 75mph back from new york to illinois.
the dirty K&N and some dirt on the compressor wheel concerns me as well.
i am just trying to find out if the cylinder walls are dusted how bad would that oil cap bounce? i have been researching everywhere and no one takes into affect every step leading to dusted walls it always seems to be focused on 1 topic.
also want to note the turbo has no shaft play not sure if these get loose and sloppy like the old 80s turbo dodges i am more so familiar with. but holding it and shaking back and forth and in and out it feels crazy tight could not pull out on it and side to side was barely possible if at all may have been my fingers sliding
here is a few pictures of my turbo.

 

Running a K&N has been known to dust these engines!! Not saying that is the case but VERY possible.
I'm not sure how much movement you should get with the oil cap but I know I have tested mine just for grins and it does not move at all. Hopefully someone will chime in with more info and ideas.

Have you done any oil analysis?

 

i have owned the truck less than a week plan is to yank that k&n off once the amsoil filter arrives.
yours does not move with the bottom tube plugged?
i have a video of mine without plugging the bottom tube.
once i get the oil leaks fixed i have planned on sending in an oil sample

 

Going by that video, you have no blowby which is excellent.

The oil cap sitting on top of the oil fill hole on the valve cover is just a rudimentary test though. To be precise one has to use a manometer, a gauge that can measure low pressures accurately.

Your turbo looks terrible in the pictures though. Is that dust and dirt on the compresser fins?
Is there dust and dirt in the turbo air piping? How about the air piping going into the intake manifold.

If that really is dust and dirt, the next logical step would be a compresssion test, which is time consuming on these engines.

A boost gauge would tell you how your turbo is performing.

Lots of other things to check out that used truck. It's used so there are going to be other issues. Be prepared for that but hopefully nothing major.

 

its dirty it has the stupid plastic k&n pipe so no dirt really stoke there i have yet to pull the intake pipe it has all hard pipes so i havent wanted to yet maybe i will get at that right now

 

pictures of pipes going into intake after Intercooler

 

What year is truck? Where did the truck come form?

I live in New England and my 2004.5 has seen every winter and salt and the turbos have never looked like that one does. Is the finish just corroded or can you wipe it with a rag and dust/dirt wipes off? I am thinking dirt is either coming thru filter or sucking in from some other place beside thru the filter. The neck on the turbo that the rubber boot should seal against should be clean where the rubber is sealed against the aluminum and it is not?

The corrosion on the outside of the turbo looks like the truck was submerged in salt water..

 

truck is from new york was not a flood victim but looks like most stuff up here in the salt belt.
was a commercial use vehicle so no one was really keeping it clean under the hood.
i believe the turbo is dirty just due to the use of the crummy k&n air filter. but as u can see the pipes after the intercooler going into the intake are clean it appears.