I have never heard of using this stuff in gas tanks...

http://www.vaxxine.com/hyoomik/images/technique1.html

but I have heard of putting alcohol into the tank , which mixes with the water, and then disolves in the fuel...

This site seems to equate the two... except that the Hydrate is more poisonous...

http://www.recochem.com/cdnav/cdprohsfaq.htm


And it may be more expensive than plain old alcohol.....