I used to work at a motorcycle shop. It was there I found a product for this issue. It's called Kreem. It is a system that prepares a tank(cleans), then lines it. I'm not a big fan of the lining part, but the cleaner works great. I think it's sulfuric acid, and it can be bought without the lining part. The reason I don't like the lining part is that unless you do it exactly correctly, it will flake off.
Einstein, when describing radio said "Wire telegraph is like a very long cat. You pull his tail in NY and he meows in LA. And radio works the same way: you send signals here, they receive them there. The only difference is that there is no cat."