Our tractors have just set around since last fall... We burn the
cheapest, nastiest, mogas we can find... We do not use Stabil, etc...
Drag the battery charger over to the tractor... Give the battery a 5
minute buzz to wake it up from laying around for five and a half
months, jump on, pump the throttle, hit the starter, and away we go...
Dunno why your gas goes bad, mine doesn't...
Now, if you leave the tank nearly dry and let it evaporate down to
sticky crud in the bottom of the tank... Pour fresh gas in, washing the
crud into the carb... Then your gas has gone 'bad'...

denny