I have a very rusted gas tank on an old Bobcat. It is part of the frame and, therefore, it is not removable. i am (obviosly) trying to eliminate the rust, but most methods require shaking the gas tank. I am considering three options. I just came across Evapo-Rust while at the auto parts store today. It would be kinda expensive because I need about eleven gallons to fill the tank. Second plan would be to cut a hole in side-wall of tank/machine; brush/clean inside of tank; fashion some type of cover that would be a little bigger than the hole. Third plan would be to add a tank; sort of like an auxillary tank; but it would be the only usable tank. Anybody try any of these? In advance, thanks for your input. PS, I also plan to visit a radiator shop to see if they can help. Meldawg