Why is warming up your car bad?

Joined
Nov 25, 2005
Messages
107
Location
Ohio
I've been reading a lot on here that letting your car warm up for a few minutes in the morning is bad. Why? I understand I'll get worse gas mileage. But I thought I was doing my truck some good to let it warm up 5 mins before my trip to work. Only takes about 10-15 minutes to get to work. I would have to think that the oil would be warmer at the end of my trip with a warm up, rather than get in and go. TONY Vehicle is 1998 Chevy k1500 172,000 miles with the 5.7 vortec, supertech synthetic and A/C delco filter
 
Joined
Apr 1, 2003
Messages
824
Location
San Jose area, CA
Not only is the fuel mileage poorer, but NO work is being done (getting you down the road) Also it is costing you more on many metrics. So a small example, if you warm up 5 min per day x 2 per day = 10 min per day x22 day per mo= 220 min/60==3.67 HOURS per mo x 12 mo= or 44 hours per year. So how much gas do you think your car will consume idling 44 hours? Next using time, So If I went somewhere at 50 mph, YOU could have gone 2200 MILES in the same time. If it were me I would start it up and GO.
 
Joined
Jun 22, 2004
Messages
1,779
Location
Central Iowa
The vehicle warms up very slowly without a load on it. Since elevated wear happens while the engine is cold (or colder) you're better off only letting it warm up as long as it takes for the engine to build oil pressure and settle down after starting. I allow mine to warm only as long as it takes to put my seat belt on, adjust the radio, pull out of the garage and close the door. Add to that the additional potential for higher fuel dilution as it's sitting there running rich.
 

Al

Joined
Jun 8, 2002
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Elizabethtown, Pa
Excess fuel dilution and more water in oil is the result. I understand where you are coming from. Just be aware that these 2 things are the down side.
 
Joined
Sep 10, 2005
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4,959
Location
Massachusetts
Personally, I let me vehicles warm up a few minutes as well. In colder climates, I think it's a little easier on your vehicle(IMO). When it's 5, or even below 0 outside, I'd rather use a little extra gas than shift the transmission into gear at a 1600+RPM fast/cold idle. Being able to see out the windshield is a plus too.
 
Joined
Oct 29, 2003
Messages
585
Location
Ontario Canada
[Welcome!] Tony. Don't worry about added gas usage etc. The price of gas is cheap compared to a rebuilt or new engine. The guys from the southern part of USA have no idea how cold it gets up here in the North. Have them stand outside in -10 to 20 deg F and scrape a frozen windshield and see if they warm their cars up. Starting a car in 50-60 deg. F is not a cold start in my books. Zaedock is correct. I also let my cars warm up a few minutes if it's below 32 deg.F. On some of the coldest days & nights below zero deg.F, I'll warm up for 5 minutes.When it's above 32 deg F, I'll let it idle for 30 seconds. The most important thing is to drive off slowly. [Cheers!]
 
Joined
Oct 25, 2005
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167
Location
ottawa ontario
I let mine run long enough for idle to stabilize and oil to circulate...and clear windows. So depending on temperature and snow/ice conditions in the morning (car is stored outside)...the time can vary from 1 minute to 10 minutes. Typically, about 2-3 minutes...then I drive gentle until it warms up.
 
Joined
Jan 16, 2003
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4,478
Location
Southern California
Excessive water and fuel dilution in motor oil from extended cold idling (more than 30 seconds and which is additive with each successive cold startup) causes far more stress than just driving off easily after a maximum of 30 seconds' idling time. Excessive water and fuel dilution comes back to haunt you not only in the form of premature engine wear, but sludge and varnish deposits, as well as premature catalytic converter and general exhaust system failure, too. Weather permitting, get your ride out on the weekend for 25 or 30 miles of sustained 40 mph or faster driving to help "blow" the contaminants out of the motor oil.
 
Joined
Jul 7, 2005
Messages
540
Location
Fla
I used to live in Chicago and the winters were bitter. We used dip stick heaters for the engine so the warm up wasn't needed. But it was so cold I still tried to get some heat before going. It got down to 68 today that is cold enough for me. [Cool]
 
Joined
Oct 9, 2004
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6,496
Location
New Braunfels
De-icing should be common sense. A cold climate will make you appreciate covered or even garaged parking. The thing is the rest of the drivetrain is not warming up as you are warming the coolant enough to get the windows to defrost. So take it easy no matter how warm the air coming out is the car can still be very cold. I drive really gentle when it is cold. After a really cold start you can feel the car loosening up as the fluids get warm and start to circulate better. (this is especcially apparent at work in the arctic-35 and colder can make a vehicle really start to behave differntly) I agree that you should begin driving as soon as it is safely rand reasonably possible.
 
Joined
Nov 3, 2002
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PA
My rule is one second at idle for every degree below freezing. +22F = 10 sec at idle, +12f = 20 sec at idle and so on.
 
Joined
Oct 14, 2005
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Schafflund, Germany
It seems that some people like to enter the high speed traffic or urban stop-and-go with the cold engine better than to follow a well-considered warm up procedure. 5-6 minutes at 1400 - 1500 rpm with the cab heater turned OFF. I have already mentioned that in another post, need to find out how people reacted to it...
 
Joined
Oct 25, 2005
Messages
167
Location
ottawa ontario
quote:
My rule is one second at idle for every degree below freezing. +22F = 10 sec at idle, +12f = 20 sec at idle and so on.
-40F = 72 seconds? [Canada] That won't work for me when its that cold.
 
Joined
Feb 24, 2005
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Southeast Louisiana
2KBMW Member Member # 2714 Icon 1 posted December 26, 2005 07:11 PM Profile for 2KBMW Send New Private Message Edit/Delete Post [Welcome!] Tony. Don't worry about added gas usage etc. The price of gas is cheap compared to a rebuilt or new engine. The guys from the southern part of USA have no idea how cold it gets up here in the North. Have them stand outside in -10 to 20 deg F and scrape a frozen windshield and see if they warm their cars up. Starting a car in 50-60 deg. F is not a cold start in my books. Zaedock is correct. I also let my cars warm up a few minutes if it's below 32 deg.F. On some of the coldest days & nights below zero deg.F, I'll warm up for 5 minutes.When it's above 32 deg F, I'll let it idle for 30 seconds. The most important thing is to drive off slowly. [Cheers!]
quote:

If I lived in that cold a climate, I wouldnt even change my oil or do any other maitnance, the salt on the roads would destroy it long before my lack of maitnance. [crushedcar]
 
Joined
Feb 20, 2005
Messages
1,183
Location
Vermont
I've taken to waiting for the idle to settle and driving easy for several miles. To some extent with my previous car that was carburated, I had to wait some 10 minutes or more in the cold for the fast idle cam to kick-off, otherwise the auto would be shifted with the engine at 2-2.2k rpm...not a good idea! I eye my oil pressure guage to better let my conscience go as for when I'm fine to work the engine further (not reaching circulatory bypass setting through the operating rpm range), but not every one has an incremented guage to view. Many have noted and I'd be very close to agreeing that an average of 15-20 minutes of easy driving after start-up, should be about enough time for the oil to be very near/at operating temp. In extreme cold add time, and decrease a little in hot ambient temperatures. Ultimately, safety rules...so take extra idle time to help defrost. I remember having to scrape the inside of my windshield when it would all of a sudden frost over from the moisture coming from my hands and breath while I was driving. [Eek!]
 
Joined
Oct 28, 2002
Messages
48,018
Location
Everson WA - Pacific NW USA
The only time I let my old beater idle for warm up is when I have NO option. Where I used to live the car would be encased in ice, I mean completely. I would allow the swede to idle while I chunked and chipped.....basically zero visibility or idle the car?
 
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