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Is it smart to warm your car up?

How long should I let my car warm up in the winter?

I have been reading mixed reviews about how long to let your car warm up before driving in the winter months. Most of the articles say that the best way to warm it up is to let it idle for 1-2 minutes, then drive gently until it reaches its optimal temperature. My concern is the following: When I start the car in cold weather the tachometer usually sits around 1500 rpm — 1750 rpm. When it has been running for a while it idles at 750 RPM and the car runs much smoother when it’s at this point. It takes almost 10 minutes of idle to get it warmed up to 750 rpm (in about -10* weather). Is it smart to idle and wait for it to get to its regular RPM before driving off?
Will driving off before it gets to a low RPM be harmful to the car in the long run?

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asked Dec 2, 2013 at 19:43
Frantumn Frantumn
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When a professional athlete warms up in the cold they do a gentle jog, they don’t sprint because they could damage something and they don’t walk slowly because it does not warm their muscles quickly enough. It is not too different for your car, the best way to warm your engine is to drive it carefully (don’t floor it and don’t idle it).

Oct 31, 2019 at 11:00

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I would agreee with the articles — waiting a minute or so (generally the time it takes to clear the ice off the windows. ) is generally fine.

As the other answers say, the engine will idle high to start with, as the ECU compensates for the colder block and thicker oil by running the engine richer. This will cause more wear to the engine, as the oil is thicker and so won’t lubricate as well as normal, but it will do so whether you are stationary or moving, so you might as well be moving. The key thing is to make sure the engine gets a chance to warm up properly over the course of the journey — lots of short journeys in cold weather will be bad for the engine as the wear will be proportionally higher.

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answered Dec 3, 2013 at 11:07
Nick C ♦ Nick C
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I’d also add (the obvious) that one should keep their acceleration and engine speed tame while the engine is warming up. The less load the better, but as you said, there’s no sense in just idling.

Feb 17, 2015 at 5:34

Lots of people have some sort of engine heater that they run for 5-20 minutes before turning the car on —> heating the engine up before starting in cold weather helps reduce the wear and tear of having the engine running with cold oil.

Jun 29, 2017 at 16:28

One other thing to keep in mind when letting a car warm up. You’re only warming up the engine. Remember all the other components that stay cold until driven: rear end, shocks, suspension components, tires, etc. So even if you let a car warm up until the engine is closer to operating temperature, you should still drive easy at first, until all components have been brought up to operating temperature.

answered Dec 9, 2013 at 13:27
Brett McCann Brett McCann
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Yes. You should allow your engine to warm up a bit.

If the temperature is exceedingly cold, say -10c, you would want to allow an extra minute or two to heat up and even out the temperature between components a bit.

If you were to start you car in extremely inclement conditions and raced it full throttle up a hill with high load there would be a potential for differing expansion rates of material. The head gasket between the crankcase and the cylinder head could show weakness as the differing expansion expands one component a bit more than the other and over time weaken adhesion between the two surfaces resulting in a failure.

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Another component of extreme cold is the thickening of oil. As @Nick.c stated. Thick oil can become an issue, it’s difficult to pump and the majority of it’s lubrication properties can be effected in extreme cold. Allowing the oil to heat and the various components to heat up is a good idea.

Additionally, since we are here, I would like to dispel some myth’s about engine heating in the morning. There is quite a bit of attribution that IMO is myth.

Would like to clarify a few points of interest

There are several myths regarding why older engines are required to warm up slowly.

Myth 1

Carbureted engines needed to warm-up longer because of the carburetor.

Running a carburetor on choke doesn’t ruin your engine. It will run rich. It can foul your spark plugs if it doesn’t come off choke, it can build up a little extra carbon in your combustion chamber over the years but it will not damage your engine. In fact, there are a lot of benefits to your engine when it runs richer. The exhaust is cooler and it’s easier on your exhaust valves and it lubricates the valve face impacting the valve seat

Myth 2

Allowing your car to warm up is a waste of fuel

That’s what is called a Straw Man argument. The question was «How long should I let me car warm up in the winter?» The waste of fuel response is a legitimate environmental concern. That is not what this is about.

Myth 3

You don’t have to warm up new engines they’re made out of aluminum that was a procedure for old cast iron blocks.

Cast iron blocks don’t crack when run from cold. False claim. Where are the citations on this?

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Myth 4

When the engine first starts in cold weather, the oil is warming. The rings on the pistons are reseating, from being cold

The rings are reseating is not something that happens. They are already seated and worn in from use. Running the engine at idle and allowing it to warm will not reseat the rings.

Myth 5

your engine needs a chance to get the oil circulated through it

The engine has oil circulating in it almost immediately. This does not take but a moment. False claim.

Myth 6

The aluminum piston will expand quicker than the the steel cylinder liner and you would seize the engine.

Pistons are now made of hypereutectic alloy. Hypereutectic alloy has a lower expansion coefficient of expansion which allows for tighter tolerances than previous materials. There is point in mixing allows called the eutectic point where the mix of alloys becomes one and their lattice structures intertwine and they become ‘one’. Of course this is overly simplistic explanation for the sake of this answer.

In short, piston expansion is no longer an issue with modern vehicles.

How Much Does It Cost to Warm up a Car, and Does Heat Really Use Gas?

Jeremy Laukkonen is automotive and tech writer for numerous major trade publications. When not researching and testing computers, game consoles or smartphones, he stays up-to-date on the myriad complex systems that power battery electric vehicles .

Updated on February 22, 2020

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For decades, the prevailing wisdom was that you should allow your car to idle and warm up before hitting the road. While modern fuel injection systems and emissions controls have lessened the need, the issue remains a contentious one.

While environmentalists would argue you should never let your engine idle due to the unnecessary greenhouse gas emissions, such an edict may run thin in sub-zero temperatures. In fact, it can be unsafe—let alone uncomfortable—to drive a car without first warming up the engine.

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Should You Idle Your Car to Warm It Up?

Car stuck in snow

You should warm up your vehicle if it is carbureted. If your car is fuel-injected, then it is a personal matter of how much you can tolerate the cold.

When you have an older car with a carburetor, the engine will run smoother if it has had a chance to warm up. Older vehicles also benefit from having time for the oil to heat up, thin out, and lubricate the engine. Newer cars that use fuel injection and computer controls are good to go without idling.

Does Running a Car Heater Use Gas?

car interior vents

Running the air conditioner consumes gas, but cranking up the heat does not. Running your car’s heating system is only wasteful when you’re waiting for the car to warm up, because an idling engine consumes gas.

If you start your car and let it idle, it will use the exact same amount of gas whether the heat is on or not. Cars always use gas when the engine is running, even while idling. So there is no extra fuel cost with turning the heater on versus simply running the engine. This is due to the fact that heater systems utilize waste heat from the engine. That waste heat is either dissipated or used to warm up the interior of the car.

Is It Necessary to Idle a Car Before Driving It?

In most cases it is not necessary to idle a car before driving it. Older vehicles that lack fuel injection systems are an exception. Depending on your cold tolerance, you may need to idle the car to warm up the interior before a drive. In such cases, a block heater is a more effective way of preventing engine damage than letting an engine idle after sitting in sub-zero temperatures. Although a block heater can warm up the engine, it cannot do anything to warm the interior or defrost the windows.

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How Much Does Idling a Car Cost?

The cost of an idling engine depends on a lot of variables. The Argonne National Laboratory performed a study on three different engines, including a 1.8L Honda Civic, a 2.5L Ford Fusion, and a 3.6L Chevrolet Malibu. For each of these engines, idling for 10 minutes consumed the following amounts of fuel:

  • 1.8L Honda Civic: .026 gal
  • 2.5L Ford Fusion: .082 gal
  • 3.6L Chevrolet Malibu: .14 gal

Paying $2.90/gal for gasoline would mean that idling your car for ten minutes would cost roughly $0.08 — 0.41, depending on the size of the engine. You can use these numbers and other gasoline prices to estimate the cost of idling for shorter or longer periods. If you have a larger engine, then you have to figure it will cost more.

While a quarter here or there is unlikely to break the bank, it’s easy to see how the costs of idling could add up over time, especially when gas prices trend higher. If you drive a vehicle with an engine that’s bigger than 3.6L, and you idle for 10 minutes each day, you could be spending over $50 in gas over the course of the winter.

Is It Cheaper to Use a Space Heater to Warm up a Car?

According to the data from the US Energy Information Administration, the national average price of electricity is $0.13 per Kilowatthour (KWh). That means a 1000W plug-in car heater used to heat up your car and to defrost the windshields will cost roughly 13 cents for an hour of use. Depending on where you live, that amount may be slightly higher or lower.

This also means that, unless you’re driving a car that has an engine in the 1-liter range, it’s significantly cheaper to run a space heater for an hour than it is to idle for ten minutes.

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