This was no big deal, but I thought I'd share it with the weathering "community." It was really just black chalk, tape, and Dullcote. This was a Bowser 45' 100-Ton Coal Hopper, factory "patched"(note the quotes)CSXT. I made it truly patched. I taped over the lettering, and let 'er have it with black chalk. Sealed with Dullcote. The bottom was just some rusty areas and splases of oily-colored "stuff."
Pretty easy.