Should I Let My Car Warm Up Each Morning?

| 10/1/2008 12:00:00 AM

Tags: cold start, gas mileage, engine warm up,

Snow CarIs it best to let my car warm up in the morning when it’s really cold? Or does that just waste gas?

Logan Widmore
Pocatello, Idaho

Although you might think it’s easier on your car to let it sit and gently warm up, doing so is a bad idea for a number of reasons. Most importantly, it does indeed waste gas.

The vast majority of cars on the road today use electronic fuel injection. When your car’s engine is cold, the computer tells the fuel injectors to stay open longer, allowing more fuel into the engine to help it run cold. As the engine warms up, the injectors let in less fuel and everything returns to normal, so to speak. 

The problem is, letting your car sit and idle is the slowest way to bring it up to operating temperature because it’s generally sitting in your drive at just above idle speed. And this method to warm up also invites other problems. Remember that modern cars are equipped with a multitude of devices to help them run clean, including a catalytic converter (sometimes three of them), a device in the exhaust system that works to burn off unburned hydrocarbons in the exhaust stream. A cold engine emits a far higher percentage of unburned hydrocarbons than a warm engine. Unfortunately, the average catalytic converter can’t process 100 percent of unburned hydrocarbons even in the best of times. Importantly, the catalytic converter needs high exhaust temperatures to work properly. Throw in a cold engine emitting a high percentage of unburned hydrocarbons, repeat several hundred times, and you can end up with what’s called a “plugged” converter. In a nutshell, the converter becomes overwhelmed and literally ceases to function. This won’t happen all at once but over time, the end effect is the same: poor mileage and significantly dirtier exhaust.

The best bet? Even when it’s 10 degrees F outside, start your car, let it run for 30 to 60 seconds to get all the fluids moving, then drive off gently. Your engine will warm up faster, your exhaust system will get up to temperature faster so the catalytic converter can do its thing, and you’ll use less fuel. Which is what you wanted all along anyhow, right?

8/30/2014 8:27:49 AM

Car engine warm up needed for car starting and generally we are focused for the best cars and the servicing point to be for that. So just for better service select the best alternative car station and the mechanics.

5/22/2013 11:09:37 AM

I agree with this article - idle running is a waste of fuel and harms the environment and eventually us who inhale all these dangerous fumes. I live in Sweden and winter is quite cold.  We could have -4 to -13 degrees fahrenheit or even colder and Idle running is only allowed for 1 minute here in order to minimize air pollution. The best and most effective way to warm up a car on a cold winter morning is to install an electric engine heater together with an interior heater.  I have this installed in my car and it's really a blessing to hop in a pre-heated car not having to scrape the frost and snow on the windshield, windows and rear window every morning.  All I need to do is plug in the heater in a wall contact with a timer (30 minutes to 1 hour will do)  and voila -the car is ready for use!  I'm attaching the link of the 2 leading companies who manufacture and sell this equipment.  I highly reccomend these products.  It will not only give you warm comfort, but it also makes the engine happy by minimising engine wear due to numerous cold starts, as well as saving the environment.


5/12/2013 12:29:38 PM

accually! i just boughht a used (modern car) and it makes a weird ticking sound when its running, well it turns out the reason it does this is because the previous owner would basically turn the car on and drive away without letting it warm up for a few minutes. modern cars have aloty shorter pistons then older cars, older cars have long pistons so there stable going up and down the cylenders, modern cars have shorter pistons so when you drive off when its cold the pistons arent going up and down properly in the cylender there wiggleing from side to side causing this to wear your pistons! you definitly need to warm up your car befort you drive it!! if you dont your pistons eventually will sound like mine! its nothing huge, i was told to use thicker oil and use a lucas oil stabilizer to protect the pistons from more wear. carefull what you read and hear look into every aspect of it.

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