Generator Winter Storage Table
| Interval | Action | Why |
|---|---|---|
| Every 30 days | 15-min run under ~50% load (fridge + space heater) | burns condensation, re-circulates stabilized fuel, keeps the carb seals wet |
| Every fill | Fuel stabilizer, 1 oz per 2.5 gal | E10 ethanol blend phase-separates in 30-90 days of sitting |
| End of season | Carbureted: run the carb dry; fuel-injected: near-full tank + stabilizer | dry carb = no varnish; FI systems tolerate stored fuel, carbs do not |
| Before first freeze | Oil to 5W-30 (or synthetic 5W-30 below 40°F) | thick cold oil is the second no-start cause after stale gas |
| Storage spot | Dry, off concrete, away from windows; never indoors or garage-attached living space | CO kills silently - storage and running have the same rule |
| Oil grade | Temp range | Note |
|---|---|---|
| SAE 10W-30 | 40°F to 100°F | the default most manuals ship with |
| SAE 5W-30 | below 40°F | winter grade for cold snaps |
| Synthetic 5W-30 | -20°F to 100°F | one grade all year if you only touch it twice |
Generators almost never fail during the storm - they fail at the start of it, after months of sitting. The pattern is always the same: the unit ran perfectly in the spring, sat all summer with a tank of E10 ethanol gasoline, and on the first cold outage night the carburetor is varnished, the fuel has phase-separated, and the pull cord yanks on a machine that cannot fire.
Bottom line: the whole discipline is three habits - stabilizer at 1 oz per 2.5 gallons every fill, a 15-minute run under real load every 30 days, and the right storage posture for your fuel system (run the carb dry if carbureted, near-full tank plus stabilizer if fuel-injected). None of them cost more than a few dollars; the first one prevents the classic no-start, the second one proves the machine still works while starting it still matters.
The honest part: a generator that has sat for six months deserves suspicion, not trust. Assume the fuel is stale, give it fresh gas and stabilizer, and test it under load before the forecast turns - a no-start discovered on a sunny Saturday is a chore, the same no-start discovered during an ice storm is an evacuation.
How to use
- Write down the date of your last real run (a 15-minute test under load counts; a 30-second start-and-kill does not) and check it against the interval table above.
- Before storage: top off with fresh fuel plus stabilizer, run 5 minutes so the treated fuel reaches the carb - or run it dry at the carb if your unit is carbureted and the season is over.
- Set a monthly reminder for the test run: fridge plus a space heater for 15 minutes is roughly the 50% load that burns condensation and keeps seals wet.
Frequently asked questions
How long does gasoline last in a generator?
Straight E10 from the pump starts degrading in 30-60 days, and ethanol-blended fuel can phase-separate in 30-90 days of sitting - the ethanol and water drop out and leave a layer the engine cannot burn cleanly. Treated with stabilizer, E10 holds for about 12 months; stored in a near-full, stabilized tank, most manufacturers call a season fine and a year the service limit.
Should I run my generator dry for storage?
Carbureted: yes - run the carb dry (fuel valve off, engine runs until it stops) so no varnish bakes into the bowl over winter. Fuel-injected: no - these systems tolerate stored fuel; keep the tank near full with stabilizer so there is minimal air space for condensation. The wrong choice either leaves varnish or leaves air, and both are winter-long problems.
What oil should a generator use in winter?
Below about 40 degrees Fahrenheit, switch to 5W-30; synthetic 5W-30 covers roughly -20 to 100 degrees all year if you only touch the machine twice a season. Cold-thick oil is the second most common no-start cause after stale fuel - the starter spins but the crank drags through cold honey.
How often should I test-run my generator?
Every 30 days, for 15 minutes, under real load - about half its rating, like a fridge plus a space heater. A brief idle start-and-kill does almost nothing: it charges nothing, dries nothing, and proves nothing except that the battery had surface charge that day. The monthly loaded run burns off condensation, circulates stabilized fuel, and finds the dead starter relay while the store is still open.