So, at the Mitty last month, I was hanging out with Lee and one of his buddies from NC, and we decided to check out some of the vendors who had tents set up. One of the vendors was a company called Evapo Rust, and they make a solvent that removes rust from metal parts, that is supposedly (hopefully) safe to both metal parts and to skin.
They handed out small samples, which I tried on some nuts and bolts and it appeared their product worked well. So, I ordered a gallon of their stuff, and poured in into my rusty gas tank. I had purchased the POR kit gas tank kit, had drained the tank, washed it with their cleaner, rinsed it and let it dry.
I thinking about having the tank dip stripped, but hadn't gotten around to dropping it off, before using the POR etching primer and sealer.
Given this state of affairs, I decided to buy a gallon of the Evapo Rust and pour it in the tank. I then stood the tank on its side and left it overnight. When I turned it 90 degrees, I was so impressed with what I found I decided to take and post this picture:

I'm not affiliated with these guys; just passing along a positive experience.
They handed out small samples, which I tried on some nuts and bolts and it appeared their product worked well. So, I ordered a gallon of their stuff, and poured in into my rusty gas tank. I had purchased the POR kit gas tank kit, had drained the tank, washed it with their cleaner, rinsed it and let it dry.
I thinking about having the tank dip stripped, but hadn't gotten around to dropping it off, before using the POR etching primer and sealer.
Given this state of affairs, I decided to buy a gallon of the Evapo Rust and pour it in the tank. I then stood the tank on its side and left it overnight. When I turned it 90 degrees, I was so impressed with what I found I decided to take and post this picture:

I'm not affiliated with these guys; just passing along a positive experience.