2011 Mack CXU613 Pre Purchase Inspection

I had one looked at this afternoon by my shop. There were a few issues found. The truck has 260k miles. I'll list the issues in order of least concern.

-O ring where oil filler meets the engine is leaking.
-There's a little play in the steering shaft.
-There's some play in the right front axle king pin.
-There is ammonia residue along a seam in the exhaust pipe after the DPF.

This last one scares the crap out of me. They said there are any number of things that could couse this. According to the maintenance records the DPF was just baked as part of a lease end service to sort the truck out before selling it. See pics:

 

MP7 engine.