I am a small tractor business who sells new and used tractors and equipment. I also work on customers tractors. Well I have a tractor that I am working on that has rust inside the gas tank. I know there is a product you can add to the tank which will help the filter from stopping up and seals the rust against the walls. Does anyone know of such a product? The customer is not financially able to buy a new tank for me to install. Thanks just lost in Texas.