On Wed, 15 Oct 2008 19:13:24 -0400, "mmc" wrote:

I've always gone by the dump it after 60 day rule.

That's way too conservative. It should be good for at least 6 months
under normal storage conditions, a year or more if a bit of Sta-Bil is
added.

The important thing is to not let stale fuel stand in the carburetor
or injection system. Disconnect the fuel hose and let the engine run
out of gas before leaving it unused for more than a month or so.