Should I warm up my car in winter, and for how long?

Updated October 26, 20269 sources3 min read

Short answer

Not for long. A modern fuel-injected car is fully lubricated within 20 to 30 seconds of starting, so start it, give it about 30 seconds to a minute while you buckle up, then drive off gently and skip hard acceleration until the temperature gauge starts to move. Driving warms the engine faster than idling, and long idling just burns fuel; the main reason to idle longer is to clear ice and fog from the windows so you can see.

Safety first. Never warm up a car inside a garage attached to a house, even with the garage door open; carbon monoxide is odorless and can kill. After a snowfall, clear snow from the tailpipe before starting, because a blocked exhaust can fill the cabin with carbon monoxide.

On this page

Step by step
Why 30 seconds is enough now
How long to idle, by situation
What long idling actually costs
Carbon monoxide: the part that matters most
Making cold mornings easier
Follow-up questions
Sources

Step by step

1
Clear the tailpipe and get the car outside
If it snowed, dig out the area around the exhaust pipe first. If the car is in an attached garage, back it out before letting it run.
2
Start it and give it 30 seconds to a minute
Most manufacturers recommend driving off gently after about 30 seconds, and Consumer Reports says about a minute on a cold day is sensible. A cold engine idles fast, around 1,200 rpm or more, which spreads oil quickly.
3
Clear every window while it runs
Scrape ice and brush snow off all the glass, lights and roof, and turn on the defroster. If the windshield still isn't clear, keep idling until it is; seeing out is the one good reason to idle longer.
4
Drive gently for the first few miles
Accelerate smoothly and keep the revs moderate. Consumer Reports says to avoid revving hard until the temperature gauge moves off the cold reading; NAPA says to take it easy for the first five to 10 minutes.
5
Give older or carbureted cars a little more
AAA suggests about 2 to 3 minutes for older cars, especially carbureted ones, and a few extra minutes in extreme cold.
6
Use a block heater where it gets very cold
In sub-zero weather, plugging in a block heater a couple of hours before you leave gives the engine a head start, according to NAPA. It also makes the car easier to start.

Why 30 seconds is enough now

Older carbureted engines needed a real warm-up before they would run smoothly. Fuel injection and engine computers changed that: the engine adjusts its fuel for the cold on its own, and oil reaches the moving parts within 20 to 30 seconds (Consumer Reports). The Department of Energy and FuelEconomy.gov both say most manufacturers recommend driving off gently after about 30 seconds, even in cold weather.

Driving is also the fastest way to warm the engine, and the catalytic converter that cleans the exhaust, because the engine is working instead of just ticking over. That means heat in the cabin sooner, not later.

How long to idle, by situation

Situation	Idle time	Source
Modern fuel-injected car, normal winter morning	About 30 seconds to 1 minute, then drive gently	DOE, FuelEconomy.gov, Consumer Reports
Older car, especially carbureted	About 2 to 3 minutes	AAA
Extreme cold	A few extra minutes	AAA
Windshield iced or fogged	Until you can see clearly, then go	DOE (idle the minimum needed to defrost)
Electric car or hybrid	No warm-up; preheat while plugged in	AAA, FuelEconomy.gov

What long idling actually costs

Fuel. Idling gets zero miles per gallon and burns roughly 0.2 to 0.5 gallons an hour (Jalopnik). Ten minutes every morning adds up over a winter.
Wear. Until it warms, the engine adds extra fuel because cold fuel doesn’t vaporize well. NAPA notes that can wash oil off the cylinder walls and thin the oil. Idling stretches out that phase; gentle driving shortens it. If you do a lot of short cold trips, stick to your oil-change schedule (see how often to change oil).
Fines. Idling is a fineable offense in some states and cities (DOE).

Carbon monoxide: the part that matters most

Carbon monoxide has no smell or color. The CDC says never to run a car or truck inside a garage attached to a house, even with the door open. After a storm, check that the tailpipe is clear before you start; a blocked exhaust can fill the car with carbon monoxide quickly.

If you’re ever stranded in snow, the CDC’s guidance is to run the engine and heater for about 10 minutes per hour, crack one window, and keep the exhaust pipe clear. Our winter car emergency kit page has the full stranded-in-snow checklist. Symptoms of carbon monoxide poisoning include headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion; get to fresh air and call 911 if anyone has them.

Making cold mornings easier

Block heater where it gets well below zero: plug it in a couple of hours before you leave (NAPA). AAA puts the part at about $50 to $200 plus installation.
Battery older than about three years? Have it tested before winter; cold is when weak batteries quit. See why a car won’t start in cold weather.
Iced windshield: defrost on full heat, then a plastic scraper; never hot water. See how to defrost a frozen windshield.
Door or lock frozen shut: push the door in, then pull; de-icer or hand sanitizer on the key for a lock. See how to open a frozen car door or lock.
Fogged glass that won’t clear: use the defroster with the A/C on and recirculation off. See windshield fogging up.
Gauge never warms up, even after 15 minutes of driving? That points to a thermostat stuck open, not to needing more warm-up time. See temperature gauge stays low.

Common follow-up questions

Is it bad for the engine to drive right away when it's cold?

No, as long as you drive gently. Consumer Reports' chief mechanic says modern engines are fully lubricated within 20 to 30 seconds, and the engine may not be warm by the time you buckle up, but it's okay to drive. What to avoid is hard acceleration and high revs until the temperature gauge starts to climb.

Is idling for 10 or 20 minutes bad for the car?

It wastes fuel and doesn't help the engine. A cold engine runs rich (extra fuel) until it warms up, and NAPA notes that this extra fuel can wash oil off the cylinder walls and thin the oil, which can speed up wear. Idling also warms the engine more slowly than driving, so you spend more time in that rich, cold phase.

How much gas does idling use?

Jalopnik, citing averages across vehicles, puts idling at about 0.2 to 0.5 gallons per hour. The Department of Energy says idling for more than 10 seconds uses more fuel than turning the engine off and restarting it.

Why does my gas mileage drop in winter?

Cold engines take longer to reach efficient temperatures, and warm-up idling adds fuel burned at zero miles per gallon. FuelEconomy.gov says a gas car's city fuel economy is about 15% lower at 20°F than at 77°F, and can drop as much as 24% on short 3- to 4-mile trips.

Is remote start okay?

It's handy for clearing the windshield and taking the chill off, but the same rules apply. Only use it with the car outdoors and the tailpipe clear of snow, never in an attached garage, and keep the run time short; the engine itself doesn't need it.

Do electric cars and hybrids need to warm up?

No. AAA says EVs and hybrids don't need a warm-up, and idling them can waste energy. For an EV or plug-in hybrid, FuelEconomy.gov recommends preheating the cabin while it's still plugged into the charger, which saves battery range, and using the seat heaters instead of the cabin heater when you can.

Is idling illegal?

In some places, yes. The Department of Energy says idling is a fineable offense in some jurisdictions, including Massachusetts, Maryland, New Hampshire, New Jersey, Vermont and Hawaii and parts of California, Colorado, New York, Ohio, Utah and other states. Check your local rules before leaving a car running unattended.

Is a block heater worth it?

Where it regularly drops well below zero, yes. AAA puts the part at about $50 to $200 plus installation. It warms the engine and oil before you start, which helps the battery, gets heat into the cabin sooner and cuts the time you'd otherwise spend idling.

Sources

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