ok,my 2 cents on the paint subject.the main cause of paint flaking off aluminum finishes is the base metal(aluminum) needs to be sanded throughly with at least 180-220 grit sandpaper.you have to make sure the paqrent metal is thoughly sanded with no shiny spots,or oxidized looking spots.a good self etching primer/sealer should be applied to the finish.then it should be tacked off with a tack rag and then painted when the sealer has setup,within 24 hrs or less.
unfortunately with production of vehicles,that cant be helped,it might sit all weekend,or not setup,or not sanded properly.the key is time must be taken to get the surface clean and sanded properly to get the paint to stick.
have you ever noticed how your cars finish scratches too easily?that is because the cleaqrcoat is soft,not hard.they make many diffrent types of clear,the auto maqkers use the quickest setting clearcoat so they can push the cars out the door,if you do it yourself,get the best clear the slow setting stuff.it will set up hard and never have to worry about scratching it easy.
ive said enuf!