I used a Kreem tank liner kit. It come with acid to eat the rust out of the tank, you neutralize the rust and remove the remaining acid with water. The acid turns the rust into iron and the water neutralizes it so it can safely be poured out anywhere such as a flower bed. The kit comes with some type of alcohol which removes all remaining water and moisture. Then you Kreem tank line the tank after the preparation. I have had my tank liner in two motorcycle tanks now for over 15 years. I live in Texas so I have had no issues at all. Others say they have had issues. I'm not sure if other climates are less suitable or if the preparation didn't include the complete kit. I bought the Kreem tank liner kit that was for a car gas tank. This included enough of the solutions to do two motorcycle gas tanks.