bad idea, if you have just a few small sandes thru on a corner or edge it'll fly, but I wouldn't apply it over bigger spots, use rattle can etching primer on those spots,scuff with brown pad and then it'll be fine, non of Evercoat polyester primers bond well to bare metal, no matter what the label on the can says,and if you have some body panels completely down to bare metal, I'd suggest using epoxy primer first, for a piece of mind, it's worth to spend couple hundred bucks ,especially if you plan on keeping the car for a while