Stabilized fuel lasts a year. Dirty carbs happen sooner.

Stabilized, ethanol-free fuel will stay good in a chainsaw for about 12 months, so a spring startup after fall storage is usually fine.

The catch is what you put in the tank. Ethanol-free premium mixed with a proper stabilizer (Sta-Bil, Sea Foam, Briggs & Stratton) and stored in a sealed, mostly full tank stays usable for roughly a year. Cool and dark helps. That’s your best-case scenario and honestly the only one worth planning around.

If you used regular pump gas with ethanol, everything changes. Even with stabilizer, ethanol fuel starts degrading in two to three months. It absorbs moisture, breaks down, and leaves a gummy varnish that plugs tiny carb jets. That’s what kills stored saws, not the engine.

Symptoms to watch for in the spring: the saw pulls hard but won’t fire, it starts and dies immediately, idles rough, bogs when you squeeze the throttle, or the fuel smells sour like old paint. If it won’t start at all, the carb is probably gunked, but don’t rebuild it yet. Drain the tank, put in fresh mix, and run it through. Most “ran fine last fall” saws just need gas that isn’t six months old.

Trust fresh gas over any additive.