The funny thing is that weedeaters seem so prone to this, yet I'll let
my lawn mower sit for an entire season with fuel in it and it always
starts on the first pull. Never any problems, hot start, cold start,
etc. However, the weedeater is very, very sensitive to anything when it
comes to starting.

-Robert

Peter Duniho wrote:

30 days may be overly conservative, but that advice is valid whether or not
there is alcohol in the gas. Regular auto gas isn't as stablized as
aviation fuel, and degrades faster. As the volatile components evaporate,
you're left with a gummy residue that clogs all sorts of things.