All good info! I use coil cleaner from an a/c supply house. It's 8 bucks a gallon and will make 50 gallons., and is some bad a$$ stuff. Any aluminum prep from an Auto Paint store will cost you alot more than that. Alodine would be great to do also after the acid wash, but is very hazardous stuff. Atleast what we used at the space center was. Any of the primers listed above are good. But the acid wash is prob the most important. Remember the last coat of paint is only as good as the first. Do your prep work good and you'll have a paint job that'll take a beating.