The simple green worked nice for me. If there is any rust Google and keyword motorcycle gas tank cleaning battery charger. Using TSP or Arm and Hammer washing soda with the charger you will never Kreem or use a tank coating again. I have done many cycle tanks with phosphoric acid, evaporust, and other acids vinegar etc. The Sunbeam tanks are small and it is so easy. Inexpensive and effective what more can you ask for?