Are you sure? I was going to get some Phosphoric acid etch/prep. You can get the stuff at most any hardware store for around $15 a gallon. This stuff does 2 things, neutralizes rust (really just slows it down alot, you never get rid of it unless you cut that stuff out) and etches the metal so paint will stick better. I use POR-15 Marine Clean for all degreasing/final cleaning before painting, stuff works great! I'm sure there are other products out there that work just as well, but it's what I've had good luck with. There's really no short cuts on body work if you want it to look good, you gotta put in the time. Are you on a tight budget? If so rustoleum is an option, POR-15 or other rust encapsulating paints are ideal (there are many that do the same thing). Once you got that rust encapsulator on, you can lay your filler right on top of it while it's just barely tacky. Fillers have etching agents in them that will bond to the paint/primer, and you still have your metal treated/sealed underneath. If you go the POR route or use a similar product, a tie coat primer will be needed to bond your top coat. Tie coats are nice too because alot of them are high build. Gives you a chance to tune the panels right before paint. <img src="http://community.ratsun.net/public/style_emoticons/default/biggrin.gif" alt=":D" class="bbc_emoticon">