I’ve had a couple of bikes that were stored for years with fuel in the tanks. Nasty stuff. I cleaned them best I could and put some rust dissolver, goose shot, and drywall screws in the tank, wrapped it real well in an old sleeping bag. When the wife was away, put it in the dryer on no heat and tumbled it. No damage and it knocked all the loose stuff loose. Been running the bikes for years now with no issues.