I would run it dry if I was storeing for more than a month or run it monthly for at least 1/2 hour under at least 1/2 load (how I treat my ONAN).
For machines not used at least that often Alcohol and Gasoline do not mix well, even in the fuel tank..
For machines that are used daily.. You can safely mix a little ALchol (10 percent is pushign it) but the cost is actually prohibitive.. The enviormental impact is greater than pure gasoline.. I can not understand why it is mandated. (Well I can but I won't discuss it here).
