So as I type this my tank is on day two of sitting in its bath of muriatic acid and water to remove the rust and paint. There is a pin hole on the side of the tank and I have yet to see the bottom. All I know is that there is at least one hole on the bottom of the tank which was sealed a while ago with what looks like calk... It looks like the inside of the tank has an old kreem liner and from other threads I dont want to go with kreem. so how do you use por-15 in a tank on the website it seems to be advertised as a paint on thing. My other question is, can I seal the tank with the stuff they use to seal radiators? I plan on using an epoxy for gas tanks to seal up the holes on the outside and then doing a good seal on the inside.