Don't know if it's the same thing ( just been and looked at the can but can't read v v small print ). Used some stuff labelled Slosh Tank Sealant - mine came from Paul Beck Vintage Suplies - tried that two or three times in the past . Clean the worst of the crap out of your tank , pressure wash or steam clean , dry it , empty contents of tin in , roll tank round all ways to ensure complete coverage then drain back out and leave to dry . Seal joints etc and varnishes (for want of a better word) any loose bits that might be left and stops them floating around causing problems . Is that the stuff ?