Generator won't start in cold weather? Oil, battery, fuel and snow

Can you run a generator in the snow?

Yes, but not out in the open snowfall and never indoors. The makers agree on the rules:

• Outdoors only. Champion says the product must always be operated outdoors, in a well-ventilated area and away from doors, windows and other vents. Generac says never to run one indoors or in a garage.
• Protected from falling snow. Generac says never to run a generator directly in rain, snow or other wet conditions. Honda warns that using one in rain or snow "could result in electrocution. Keep the generator dry."
• Clear of drifts. DuroMax says the area must stay clear of snow, leaves and anything else that could block the generator's vents.

An open-sided canopy or a cover made for running generators is the usual answer. More on that below.

Why cold stops a generator starting

Symptom: The pull cord is stiff, the starter turns slowly, or it cranks but doesn't catch.

Why it happens: DuroMax lists the common causes of a cold no-start:

1. Oil that is too thick. DuroMax says engine oil can gum up when it gets too cold. Champion says weather "will affect engine oil and engine performance."
2. A weak battery. DuroMax says cold temperatures can drain batteries more quickly, including a generator's.
3. Snow blocking the vents. Falling snow can build up around the generator.
4. Skipped storage steps. That includes old fuel. Generac says fuel begins to deteriorate within about a month, and that you should add a stabilizer from the start.

How to fix it:

1. Unplug everything from the generator.
2. Check the oil grade against your manual (next section).
3. Charge the battery, or swap in a charged one.
4. Drain old gas and refill with fresh, stabilized fuel. See how to store a generator.
5. Use the cold-start choke steps in your manual. Champion's manual uses full choke when starting on gasoline below 59°F (15°C).
6. If the cord is stuck solid, see generator pull cord stuck.

Oil grade by temperature

Check your own manual first, because makers differ.

Maker	What it says
Generac	Above 32°F, SAE 30. Below 40°F and down to -10°F, 10W-30. Synthetic 5W-30 can be used in all temperatures.
Champion	Recommends 10W-30. Full synthetic 5W-30 "will aid in starting in cold ambient" below 41°F (5°C).
DuroMax	30W, 10W-30 or 5W-30 are all usable, but 10W-30 can cause problems below 0°F. It recommends 5W-30 in below-freezing temperatures.
Honda	10W-30 for general use. Other grades in its chart may be used when the average temperature in your area is in range.

Champion also notes that its generators may be run at temperatures from 5°F (-15°C) up for short periods. If the generator has been stored outside that range, bring it back within it before you start it.

Synthetic oil in Champion's manual is allowed only after the break-in period, so check yours.

Propane versus gas in the cold

Gas: Fresh fuel matters most. Old gas is a common reason a stored generator won't fire.

Propane: DuroMax says propane tends to perform well in the cold because it is already a gas. But in extreme cold it may still be necessary to use a propane tank warmer. Champion explains the limit: when a tank gets very cold, propane vaporizes more slowly and may not give the engine enough fuel. Frost on the tank and regulator is normal unless performance drops at the same time.

If it drops, Champion suggests swapping tanks so the first can warm up, and placing the tank near the handle end where the engine fan air blows out. Keep it out of the muffler's path. Never heat a tank with a flame. More in dual fuel generator won't start on propane.

Keeping snow off the intake and exhaust

• Shovel a clear space around the generator before you start it, and check again as snow keeps falling.
• Keep all cooling holes open and clear of debris, mud and water, as Honda says.
• Keep the exhaust end free so fumes can leave. Carbon monoxide kills, and snow banks can trap exhaust: see generator carbon monoxide safety.
• Stay at least 20 feet from the house, away from windows and doors: how far from the house.
• Honda says that if a generator has been stored outdoors without protection, check the control panel's electrical parts before each use, because moisture or ice can cause a short circuit.

Never run it under a tarp

A tarp is not a canopy. Honda says "do not enclose the generator in any structure," and that a hot engine and exhaust "can ignite or melt some materials," so cover it only when it is cool. A tarp pulled tight traps exhaust and blocks the cooling air.

Use an open-sided canopy, or a cover made for running generators and installed per its instructions. See running a generator in the rain for what OSHA, Champion and Honda say.

Related guides

• Generator won't start: the full checklist
• Getting your generator ready for winter

When to stop and call a pro

Stop and get it serviced if it still won't start after fresh fuel, the right oil, a charged battery and the right choke, or if you see ice or moisture inside the control panel. Run it outdoors only, 20+ feet from the house: generator carbon monoxide safety.