White milky marks (?) on left air intake vent ...

[f5fstop]

Roof rails are noted to crack where the pillar molding slides over. GM has a new supplier producing better rails, and better fitting pillar moldings. They were supposed to be out in May, but I have not seen the paperwork stating they are released. When they are released I'll post it here, unless someone else finds out first. It would be all under warranty. GM is aware there is a fit problem with the pillar moldings, and a cracking problem with the roof rails.
As for the white spots, I'm not sure what your's are caused by. I have not seen or heard of any white spots on the pillar moldings. If I were a service writer, I would have to wonder about some type of road splash.