ok heres a question. i only found rustoleum professional in the quart cans. how many cans will it take to paint a whole car? i plan on doing black. now if i need to buy quart cans should i mix all of them together first to make sure the pigment is even? i know on jambs and trunks and engine compartment it won't matter but for the surface it might. if i did one panel at a time. whats the opinion on this? also is there a base rustomleum professional that can be tinted or do you have to use the colors available? if it can be tinted i might go with something other than black.