if rust has come up through it means that the prep work was poor in the first place mate. thats not saying that the paint isnt poor also though, ive never used it. when i got my block back from the re-bore i masked off the bores and galleries and sand blasted it, then removed all the core plugs and thoroughly cleaned the whole block of swarf and sand etc with an air line, thinners and degreaser etc - minty mint. Then i applied a few coats of high temp black (cant remember brand) and job was a good'un... i dont rate any paint from halfrauds thats their own personally..