What Old Mech said.
7 year old gas in my Firefly when I got it. Ran fine.
My Swift GT parts car has 5-7 year old gas in it now, and always starts right up.
However: 1 year old gas in my old 2-stroke boat engine is iffy.
See also:
http://ecomodder.com/forum/showthrea...use-19021.html