Is it bad to let my car sit all winter? How do I keep the battery and tires from going bad?

Updated November 2, 20267 sources3 min read

Short answer

Letting a car sit is fine if you prepare it; the usual casualties are a dead battery (Consumer Reports says even a week or two parked can drain one), flat-spotted tires, and mice in the engine bay. Either drive it at least 20 minutes every week or two, or store it properly: hook up a smart battery maintainer, fill the tank, change the oil if it's due, set the tire pressure, skip the parking brake, and block the openings rodents use.

Safety first. Charge batteries only in a well-ventilated space and use a smart maintainer that shuts off on its own; Consumer Reports warns that overcharging can damage a battery or start a fire. If the car has sat for months, check for chewed wires, nests and fluid leaks before you start it, and have a shop look at anything that's been chewed: damaged wiring can short or catch fire.

On this page

Step by step
What actually goes wrong when a car sits
Driving it vs. storing it
Where the sources disagree
Before the first drive in spring
Related winter answers
Follow-up questions
Sources

Step by step

1
Decide between driving it and storing it
If the car will be parked for a few weeks, Consumer Reports' chief mechanic John Ibbotson says to drive it every week or two, for at least 20 minutes, so the battery recharges and the engine, transmission, tires and brakes reach operating temperature. Just starting it and idling in the driveway doesn't count: AAA Club Alliance says idling does little for the battery. If nobody can drive it, store it using the steps below.
2
Change the oil if it's due, and top up fluids
Used oil carries acids and contaminants, so AAA and Firestone both say to change it (and the filter) before storage if it's due. AAA also says to service brake fluid and coolant first if they're due, because deteriorated fluids can lead to rust and corrosion.
3
Fill the tank
AAA, NAPA and Firestone all say store it with a full tank, which leaves less room for moisture to condense. AAA adds fuel stabilizer and drives 5 to 10 miles so treated fuel reaches the whole system; NAPA says stabilizer isn't needed unless storage runs six months or more. Using it for a winter-long stay costs little.
4
Keep the battery charged
Clean the terminals, then connect a smart battery maintainer and leave it on for the whole storage period (AAA, Consumer Reports). A basic trickle charger has to be watched and disconnected by hand; a maintainer switches on and off by itself (Consumer Reports). If you have no outlet, Firestone's alternative is disconnecting the negative cable, after checking the owner's manual; you'll lose radio presets and paired phones.
5
Set the tires to fight flat spots
Sources differ: AAA adds 10 psi to each tire, NAPA says a few psi over normal, and Firestone says inflate to the recommended pressure (cold weather drops pressure, which makes flat spots more likely). Whatever you choose, write it down and reset to the door-jamb number before you drive. For long storage, jack stands or curved storage pads keep weight off the tread (AAA, Consumer Reports).
6
Leave the parking brake off
AAA and Firestone both say don't set the parking brake for storage, because it can rust or stick in place. Leave an automatic in Park; put a manual in first or reverse and chock the wheels (AAA).
7
Keep mice out
Clear out food and crumbs, then plug the tailpipe and engine air intake with steel wool or copper wool and set traps around the car (AAA, NAPA, Firestone). AAA says evidence for dryer sheets and mothballs is weak.
8
Lift the wipers, cover it, and leave yourself a note
Lift the wiper arms so the blades don't stick to the glass. Store indoors in a cool, dry place if you can; outside, use a breathable cover that won't trap moisture (AAA). Write down every step, including the steel wool in the tailpipe, and leave the list on the seat so you undo it all before the first start (AAA).

What actually goes wrong when a car sits

Problem	Why it happens	How to prevent it
Dead battery	Modern cars draw power even when off; cold cuts battery strength (about 30% at freezing, about 50% at 0°F, per AAA Club Alliance)	Drive 20+ minutes every week or two, or use a smart maintainer (Consumer Reports)
Flat-spotted tires	Weight sits on one patch of tread; cold drops pressure (Firestone)	Raise pressure or move the car every couple of weeks; jack stands for long storage
Stuck parking brake	Cables and shoes can rust in place (Firestone)	Leave it off; use Park or a gear plus wheel chocks (AAA)
Moisture in the tank	Condensation in a half-empty tank (NAPA)	Store with a full tank; stabilizer for long stays
Mice and nests	A quiet, warm engine bay	Steel or copper wool in openings, traps, no food in the car (AAA, NAPA)
Rusty brake rotors	Surface rust forms on bare iron	Normal braking clears light rust (Consumer Reports)

Driving it vs. storing it

Parked a few weeks (you or someone can drive it): a real drive every week or two is the simplest plan. Consumer Reports says at least 20 minutes, with plenty of braking to scrub rust off the rotors. A trip to the end of the street and back, or idling in the driveway, doesn’t recharge the battery; AAA Club Alliance calls idling a myth for battery care.

Parked all winter (nobody will drive it): do the full prep in the steps above. The two that matter most are the battery maintainer and the full tank. Everything else protects tires, brakes and wiring from slower damage.

Where the sources disagree

Tire pressure for storage: AAA says add 10 psi, NAPA says a few psi over normal, Firestone says the recommended pressure. Don’t go above the maximum printed on the tire sidewall, and always reset to the door-jamb number before driving.
Fuel stabilizer: AAA includes it even for short storage; NAPA says skip it under six months.
Dryer sheets for mice: Consumer Reports lists them as one option; AAA says the evidence for dryer sheets and mothballs is weak. Steel wool in the openings and traps are the methods all of them agree on.

Before the first drive in spring

Remove the steel wool from the tailpipe and air intake, and work through the list you left on the seat.
Pop the hood: look for nests, droppings and chewed wires or hoses. If anything’s chewed, have a shop check it before you drive.
Check under the car for puddles, then check oil and coolant.
Reset tire pressure to the door-jamb number.
If the battery won’t start the car, see how to jump start a car. A battery that keeps going flat after storage may be worn out: see why your battery keeps dying.
Brake gently a few times on the first drive to clear surface rust.

Common follow-up questions

How long can a car sit before the battery dies?

There's no single number. Consumer Reports warns that parking even a week or two can drain the battery on a modern car with a lot of electronics, and Firestone says some die after just a few days. Cold makes it worse: AAA Club Alliance says a battery loses about 30% of its strength at freezing and about 50% at 0°F. Your owner's manual may say how long your car can park and still start.

Is it good to start the car every week and let it idle?

Not really. AAA Club Alliance says idling does little for the battery, and short trips don't fully recharge it either. Consumer Reports' advice is to actually drive at least 20 minutes every week or two. If you can't drive it, a battery maintainer is the better option.

What's the difference between a trickle charger and a battery maintainer?

A basic trickle charger keeps feeding current and has to be watched and unplugged by hand. A maintainer (sometimes called a battery tender) switches itself on and off to hold the battery at full charge, so it can stay connected for the whole storage period. Consumer Reports' chief mechanic prefers a smart maintainer. Neither is meant to revive a fully dead battery.

Do I need fuel stabilizer for winter storage?

For a few months it's optional. NAPA says it isn't needed unless storage runs six months or more; AAA includes it in its checklist even for stays under 45 days. If you add it, drive 5 to 10 miles afterward so the treated fuel circulates (AAA), and store with a full tank either way.

Will my tires get flat spots over the winter?

They can, especially when cold weather lowers the pressure (Firestone). To reduce the risk, raise the pressure as AAA or NAPA suggest, have someone move the car every couple of weeks (Firestone), or put the car on jack stands (Consumer Reports). Reset the pressure before driving.

Should I disconnect the battery instead of using a maintainer?

It works if there's no outlet nearby. Firestone says to disconnect the negative cable after checking your owner's manual; expect radio presets and Bluetooth pairings to reset. A maintainer keeps the battery fully charged instead, which matters because Consumer Reports notes low charge can shorten battery life.

What should I check before driving a car that sat all winter?

Remove anything you plugged (tailpipe, air intake) and undo every step on your list. Look for chewed wires, nests and puddles under the car. Set tire pressure to the door-jamb number. Check oil and coolant. If it sat more than six months, Consumer Reports says change the oil. Expect a little grinding from surface rust on the brake rotors at first; Consumer Reports says normal braking clears it.

Can I leave an electric car sitting all winter?

Yes, with a little planning. Firestone suggests storing an EV at about 80% charge, not 100% or near 0%, and having it checked or charged at least every three months. Cold below about 40°F drains the battery faster, and features like sentry or camera modes add drain. Follow your owner's manual for its storage mode.

Sources

General information only, not a diagnosis. Your owner’s manual comes first. How we write these