Warming up your car

This question will have no relevance to those of you who don’t live in the frigid northern climes like me.

I was always taught that you need to start your car and let it warm up for a good 10 minutes or so (at least) in really cold winter temperatures, to thin up the motor oil and get it flowing and properly lubricating everything, before you go driving away.

Is this a myth? What difference does it make?

Seems like the initial act of starting the car would be when the most unprotected wear would occur, and that a minute or so would be all that was needed to get the oil pumping through the system again – if that.

I know little about such things, so I’d appreciate the Straight Dope from someone with some automobile smarts.

“In much wisdom is much grief; and he that increaseth knowledge increaseth sorrow.” - Ecclesiastes 1:18

Actually a local TV station had a mechanic on just last week who said that a vehicle just needed a minute or two prior to driving in cold weather. The big thing though is getting all that frost, ice or snow cleaned off the windows (which btw is required by law here in NY state. Something to do with unobstructed view out of the vehicle.)

Of course it depends on just how cold it is. If we’re talking anywhere from 0 to -45 degrees Farenheit you definitely want to let the car warm for at least 10 minutes. I don’t know the mechanics of it but if you doubt my word, just try to drive a car that’s been sitting all night in -35 after letting it run for only a minute. You might get it up to 10 mph in about 15 minutes.

“My hovercraft is full of eels.”

“Click and Clack” always claim that you only need to let it warm up until it will run. In other words, if your car is going to buck and stall as you pull out of the driveway, it isn’t warm enough yet, but as soon as it will move with a minimum of fuss, it’s fine.

They never put a set time on it.


As someone said, it depends on conditions. I have an open carport. I have always gone by the rule that, once the engine is started, rev it slightly – only enough to get all cylinders firing, then back off until missing re-occurs, then rev slightly again. Do this long enough (don’t forget to set the automatic choke, either) to keep the engine from stalling when you put it into gear.

Depending on the distance you plan to drive and the extremity of cold, you might consider taping a small piece of cardboard over part of the radiator.

For my money, your best best bet (providing a socket is near enough) is a simply dipstick oil heater. The only run about $10, use about 75 watts, and allow instant circulation of oil to all parts of the engine. Heat rising from the oil pan also warms the block gradually and speeds warm up in the morning.

I’m one of those Cold Clime persons… it’s minus 24 Celcius outside my window. My 'rents warm up the car for a good fifteen mniutes these mornings because it’s nice to get into a car and be able to turn the heat on without it giving you frostbite :slight_smile:

“C’mon, it’s not even tomorrow yet…” - Rupert

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Wow, caught me off guard with that email addr. I figured you owned a brewery or something. MI - you are in cold country.

Over the last 15 years just about all manf’s incorporate cold start circuits and have feedback and auto-adjusting
features for cold running conditions, for example: a fifth injector in Bausch systems or a heated grid at the inside the
venturi of Pontiac carbs.

These features defeat the problems of getting a cold block and parts to run properly like they would at the spec’ed
mid-range limits of temperature. So most cars can be driven immediately after starting. A brief few seconds delay is all
you need to insure the oil is getting around to where it needs to go and your off. But, the engine is really not warm and
the parts not yet expanded to their proper sizes.

A little more time in the driveway the closer the parts will get to normal sizes. A way to quicken the process is wait a
while at idle, then step on it to a very high idle. Your in the driveway not under load which makes it ok. Very few
people will wait for a long time so over a short warm up period it would be better to do it at a very high idle.

If your the type of person who gets a new car every few years don’t bother.

Theory says the least wear on internals can be achieved by idling at about 2k rpm just until the car is driveable (won’t stall) and then driving it gently until it warms fully. Driving under load will warm the engine quickest.

In real life the only difference the average driver will notice is the extra cost of gas for extended idle time.

A block heater will help reduce internal wear in any climate.

This is perfect timing! I have been curious about this myself. I grew up in a warm clime, and didn’t have to deal with snow until recently. And I have heard differing stories on how long to warm up your car. I have been just starting it up and running it when it’ll go without stalling. Depending on the temp., this can be 20 seconds to 5 minutes. I was told by someone to drive slow (under 35 miles) until the car was warm, which is what I do. Sounds like I haven’t been too far off.

I was just told by someone today that I should warm up the car for 5 minutes no matter what…but what a hassle. So glad to hear that it doesn’t seem to be necessary.

Speaking as someone who lives in one of the coldest large cities around (Edmonton), there are two main reasons to let the vehicle warm up for a while: The first is to get the viscosity of the oil to the right level. Try pouring some oil when it’s -30 out. It pours like molasses. So it’s not lubricating the interior of the engine very well. This isn’t as big a problem if you change to a lighter-weight oil in the winter, but lots of people don’t. Some of the synthetic oils are pretty good at maintaining an even viscosity through a wide temperature band.

The second reason to get the defroster temp into the range where it will keep the windows clear. More than once I’ve been in a hurry to get going, and my windows will flash-freeze and frost up while driving down the road, even if they were completely clear. The combination of your body heat, moist air from your breathing, and cold wind over the windshield while you drive can cause serious problems. Very dangerous. You should have your defroster blowing warm air before you get going.

A VERY good point. This is exactly how I cracked up my first car @ age 16. Safety should always be the first concern.

It really depends on the age of your car.

Mine is a 79, and simply wont run if I dont warm her up first, of course I have to sit IN the car, with the door open so I dont frost up all the windows, with my foot on the gas to keep it going, BUT HEY! it still runs.

My fathers rule of thumb (mechanic) is to run it till the heater blows warm air,then go.

Newer cars of course warm up faster.

And the comment about the breath in a clod car causing frost…right on! I actually have to scrape the inside of my windows every morning as well as the outside.

Safe driving everyone.

I have a SUV and according to the owner’s manual…you are not supposed to let the engine idle for more than a couple of minutes. It actually states in the manual that it is not good for th engine. I’m sure this has to do with warranty, and I’m sure that the repair guys will ask if you have the habit of letting the vehicle idle in the mornings because I’ve had them ask me that in the past…and they told me to stop doing it. Of course you guys live in a much colder climate. Freezing around here in winter is about normal but not minus temperatures. But it seems like a standard owner’s manual.

“Do or do not, there is no try” - Yoda

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When it gets down to 5 or 10 below zero ('F), I warm my car up for 5 to 10 minutes and it has nothing to do with what the car wants. It has to do with the fact that I personaly tend to stall at that temp and I want it warm in that sucker when I start out.

Im with Fuzz, read the manual. Mine states ten seconds. But you should be able to feel how fast things are going to know how long is the right time.

Also, change the air filter. Its only about $5 usually & it can make things a lot better on those cold days as a clean one gives more air.

That reminds me, do any of you read the manual on how to start it? They have a procedure that must be followed. So far I have not met anyone who read it other than myself.

Handy said:
So far I have not met anyone who read it other than myself.

I think we are in the minority, but I always read mine.

Two words: *trouble light[/].

This is, of course, assuming you park your car near an outlet or can safely/easily lay an extension cord.

You can either set the light under your hood to warm the oil pan and block overnight (75-100 watts will do a bang-up job even in sub-zero temps) and what you’ll pay in electric will be far less than the gas you’ll blow warming the car up mechanically. As an added touch, throw an old blanket over the engine.

As for waiting until the defroster works – you can do that, sure; or you can go to most any auto accessories store (or order from J.C. Whitney) an electric blower/defroster that heats instantly and plugs into the lighter socket. These usually come with enough cordlength to reach the rear window.

And, if you’ve got two trouble lights, you can leave one one in the passenger compartment – just be sure it doesn’t come into close touch with anything that can scorch; I usually set it up on a couple of bricks or aluminum cans.

Thank you fer yer support!

wouldn’t it be simpler to have a block heater installed? they’re pretty much standard issue around where I live.

and the stars o’erhead were dancing heel to toe

George, you forgot to mention one little item… If you “throw an old blanket” over the engine, be sure to remove it before you turn the key!

Just looking out for the lawyer lurking behind that tree over there… :wink:

I don’t know why fortune smiles on some and lets the rest go free…


Yeah, well, if you need to be reminded of something like that, especially if there’s a freaking electric cord hanging outside your partially raised hood, I guess I should remind you to wipe your poop-chute, too! :wink:

"You’ll never get as much out of being right as you will from finding out why you were wrong . . . " The Papoon Principles Ch. 1.