The rustoleum stuff is great. But if I may, give some time reading about POR-15. It is still available, and that sh*t is amazing! Yeah it's more involved than just the glop on thick rustoleum, but it's bulletproof (not literally but it is hammerproof literally). Used it on the engine bay of my Iroc, undercarriage, rearend, sfc's, and gas tank. You have to clean the part(s), basically remove all the oil and debris from it, and then hit it with a phosphorous type solution and then just paint man. No need for sandblasting. Give it a few mins to read about it man.
POR-15
http://www.por15.com/