Hey ya'll, A few years ago I painted my truck with just a flat black primer. I'm getting the itch to repaint it an olive drab. My question is with the old paint it was aerosal and after a season of lots of mud the paint is nicely tinged brown from mud soaking it and its quite difficult to wash. What is the CHEAPEST and EASIEST way to coat my new paintjob so this doesn't happen? Or should I just paint it tan? BTW This will be with spray paint again..thanks!