The Cold Truth About Warming Your Car Up in the Winter

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Drivers should heat up their car for no more than 30 seconds on an average winter day to cut down on fuel waste, pollution, harming your engine, and fogging up your windows.
On a freezing winter’s day, it’s common practice to start your car a few minutes before you’re ready to leave to get the engine warmed up. But this is a myth. It’s not necessary and many states now have anti-idling laws to deter people from the habit.
With winter approaching, the car insurance comparison and broker app Jerry is debunking the myths associated with warming up your car.

Myth 1—Warming up my car on a cold day is no big deal

Actually, it is! Warming up your car for too long wastes gas, pollutes the environment, and can harm your engine.

Fuel waste

For vehicles less than 30 years old, you’ll need no more than 30 seconds to warm your engine up—otherwise, idling just wastes fuel.
Today, electronic fuel injection systems use sensors to calculate how much gas and air are needed to pump into an engine for it to start based on temperature. Since this is automatic, most cars get just the right amount of gasoline needed to drive when the engine starts. Waiting five minutes for the engine to “warm-up” pumps extra gas into your engine—for no reason.
One cold-weather study by the Government of Canada determined that just five minutes of idling increases your vehicle’s overall fuel consumption by 7 to 14%. Idling for ten minutes means a fuel intake increase of 12 to 19%.


Idling on a frigid winter’s day also harms the environment. A2009 energy sector study found vehicle idling made up an astounding 1.6% of U.S. greenhouse gas emissions, half of which came from cold weather idling.
That figure is twice the number of emissions caused by the entire steel and iron manufacturing industry!

Engine harm

Along with fuel waste and pollution, idling for more than 30 seconds can harm your engine.
If there’s more gas than needed in the gas-air mix that starts your engine, the excess gasoline can strip oils from the engine. This decreases engine lubrication, leading to more—and faster—wear and tear.
Key Takeaway If your car is less than 30 years old, limit your idling time to less than 30 seconds.

Myth 2—It takes 5 to 10 minutes to warm up a car on a cold day

Auto experts recommend Americans warm up their engines by driving—not idling for a few minutes.
While engines take slightly longer to warm up and reach an ideal operating temperature on cold days, the EPA stands by the 30-second recommendation. On really frigid days, the EPA says you can idle your car for a minute—but no longer.

Myth 3—My engine’s oil needs to warm up to flow

Most multigrade engine oils used today are engineered to work in all weather down to -40 degrees Fahrenheit—including at start-up.
The EPA says it is ok to idle for about a minute on extremely frigid days to thin out engine oil so it flows properly. That said, most experts maintain that starting your car and driving gently for about 15 minutes ensures proper oil flow.
Key Takeaway Most engine oils are produced to flow at extremely low temperatures, ensuring your engine works when the car is started.

Myth 4—My car needs to warm up to defog my windows

Another common misconception is that you need to let your car heat up to clear your windshield. In fact, the opposite is true. The longer your car idles, the foggier your windows get!
When warming your car up, moisture finds the coldest place to settle—and that’s usually on your car’s windows. To avoid a warm car and foggy windows, here’s a trick:
  • Turn on your car’s defogger to start clearing your windows
  • Now, turn your car’s heater to high to warm up the air inside your car
  • Then, turn your air conditioner on high to pull in any extra moisture in the air
  • Next, turn all air circulation off
  • Open windows slightly to allow fresh air in
This should solve your foggy window problem. If not, keep a sock full of cat litter near your windshield to absorb excess moisture.
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Where did the myth of heating up your car originate?

The myth of warming up your engine on a cold day originates from an old truth that is no longer valid. When carburetors supplied gas and air into a combustion engine to start a car, cold weather would slow gasoline’s evaporation, leading it to condense on the intake manifold’s walls and starve the engine of fuel. The result? A stalled engine.
Nowadays (and since the mid-1980s), most new vehicles have electronic fuel injection systems instead of carburetors, which automatically calculate how much gas and air to inject into a car’s engine for it to start, based on temperature.
This means that, when starting your engine, most cars are ready to drive no matter the weather— there’s no reason to “warm” your car up, other than to keep you comfortable.
If you drive a vehicle older than thirty years, and still “warm” your car up, ask the manufacturer about how to correctly start your car in cold weather.
Key Takeaway: Electronic fuel injection systems regulate the amount of gas and air going into an engine based on temperature, negating the need to warm your car’s engine up.

What we gain by not idling

The 2009 study concludes that cutting unnecessary idling will save Americans a whopping $5.9 billion on fuel costs.
This would have an enormous impact on the planet. The same study argues emissions saved by widespread idling cuts would dwarf the emissions of the aluminum, soda ash, and limestone industries put together.
Some municipalities—such as frigid Minneapolis—have instituted heavy fines for idling more than a set amount of time each month.

Warming up with Jerry

If you follow the EPA’s suggestion and idle for no more than 30 seconds, you might be cold on your commute—but there’s nothing that warms a driver’s heart like a robust car insurance plan.
Sign up with Jerry in under a minute and this smart car insurance broker app will find you the best policy at a great rate. Jerry will sign you up for your new policy and help you cancel your old one. No forms, no phone calls, no hassles!
Best of all, Jerry users save over $800 per year on their car insurance.
“When I started shopping for insurance for my new car, the estimates I received were around $150. Jerry found me full-coverage insurance for $102. This is NOT a joke!” ––Auden D.


How long should you let your car warm on a cold day?

Most automobile experts say gently driving for about 15 minutes will get your car’s engine temperature up to its optimal performance levels. If you choose to idle your car, the EPA recommends doing so for no longer than 30 seconds (or a minute on really cold days).

Does idling damage your engine?

Idling can damage your engine. When your fuel injection system pumps too much gasoline into an idled engine, the excess gas can strip your engine of the oils it needs to operate properly. This can accelerate wear and tear on your engine.
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