I found a great gas tank cleaning process.
Buy "The Works" toilet bowl cleaner at The Dollar store. $1 per 64 oz bottle. Mix it 1 part "The Works" to 10 parts water. Let it soak for 24 to 48 hours depending how bad the rust and varnish is. Rinse with water, Coat with Ospho, dry with air gun or leaf blower.
It will be clean!

Wayne
1938 1-Ton Farm Truck
Stovebolt Gallery Forums
1989 Silverado
1996 Mustang GT convertible
When I die, I hope she doesn't sell everything for what I told her I paid for it!