Hey guys, So I bought a 1981 550 seca gas tank (lucky me these seem to be getting harder to find) that is extremely rusty on the inside, and not too bad on the outside. I'm planning on restoring the inside and repainting the outside though so the condition isn't a big deal anyway. I originally tried cleaning the inside with the distilled water and sand method, but holy **** what a work out that was. I shook that thing in every direction possible for at least 30 minutes. By the time I gave up I looked up to see my neighbor starring at me from across the yard. I cant imagine what was going through his head. Once I decided I had enough of that I decided to go get some evapo-rust. I followed the instructions and tilted the gas tank on each side and the front and back for an hour each, shaking it a little between each turn. Then i dumped the contents, by this time it was dark outside so I couldn't tell what color the fluid had become and I then cleaned it with detergent and distilled water. I brought it inside the garage, shined a light into it, and to my disappointment it still looks like hell (see pictures). (First is from the gas cap hole, second is from the float hole) I was hoping someone might have some insight into a better way to clean this. Has anyone ever gotten every bit of rust off the inside as far as you could tell? Ideally I would like this thing to look brand new on the inside, but realistically at what point do I stop and just re-line the inside of the tank?