Hipster
I'm Awesome
Before my very informative reply was clowned by a new guy, causing my response to him to get deleted, my explanation of the advice was to avoid spraying WD40 (or similar products) on painted areas because it can cause fisheyes on any future paint work. Anybody who doesn't believe this is welcome to look it up.
Richard
I've had quite a few paint jobs ruined by stuff being sprayed at the other end of the shop when I painted in a cross draft booth. pb blaster etc. Painting one in a garage where there had been a bunch of mechanical stuff done doesn't always work well either.Fish eyes are a pain to deal with. I've only painted a hood and a fender, DIY type of work...but have a little more knowledge on finishes in general in wood and metal (lacquer, oil, acrylic, 2k urethane basecoat/clearcoat, etc.) and so I am aware of them. My friend that does body work has some stories where he lost literally a week's worth of work from fish eyes showing up on the clear final coat of a complete repaint job. It happens and it's a real problem from wax, sillicone and oil contaminations.
I really like this site and have learned a lot, but sometimes simple statements get blown out of proportion by folks. Hats off to Moderators for keeping everything in order.
As far as the belt molding I always preferred to at least loosen up the mirror. While you have the molding bowed up and jacking around getting the rear tucked in you risk marking the molding and it's exposed once you get the molding in position. Sometimes that matters especially to a customer that paid you to install new ones.