Stay away from the methanol.


Agreed, methanol is bad, you should use Ethanol instead. It is
virtually identical to methanol in antifreeze properties, but is non
toxic and certainly biodegradable. Plus you can use any leftover
ballast as a pre-chilled refreshing post flight celebration beverage.

You can also make it yourself for just pennies a gallon.

http://www.appropedia.org/Amal's_ethanol_still

Just be sure to keep your eyes peeled for those dang revenuers.