letting your car warm up

[The Calculus of Logic]

Is there any antidotal evidence saying that letting your car warm up before you drive it is easier on its parts than just starting it up and driving it? If you let your car warm up, it takes 15 minutes, but if you drive it slowly it warms up in 5 minutes. What is the difference? Is it worth the inconvenience?

Does this go on Great debates or here?

[SlickRoenick]

I don't like starting my car and letting it idle when it's cold. Cold engines are bad. So once I get in i drive it, but daintily. My mom on the other hand tries to top 50 mph backing out of the garage regardless of the car temperature or what's behind her.

[cw]

I've heard to just drive it and it will warm up. This may not be true for older cars/trucks (albeit that need a tune-up). With my truck, I have to start it on cold mornings or risk stalling out in the middle of an intersection, not good. Logic tells me that since it runs better warm (being when the water temp. is warm enough to defrost the windows), then yes, letting it run makes a difference.

[something clever]

it mostly has to do with expansion rates and oil pressure..

at idle the combustion pressures are much lower than when driving.

when a car is really cold the oil DOES become thicker, just like in those old commercials.. one could assume oil that has the viscosity of molasses doesnt flow well and might not get a chance to circulate throughout the engine and lube all the bearings enough... idling puts very low stresses on parts because its at such a slow speed (~500rpm-1000rpm) that its less of a problem..

[don't ask]

I have frequently heard that it is a bad thing to warm up your car.

For example:

ENGINE START UP
Question: How long should I warm my car up before driving?

Answer: In almost all circumstances you should NOT warm up your car before driving. This is the most destructive time for the engine and its related parts The quicker it warms up the better. Your car will warm up much faster driving than just sitting there idling and you will save fuel.

From this site (http://www.sierraauto.com/myths.htm#startup) by an auto dealer.

[Reeder]

COOL IT ON THE WARM-UPS
For years, you've been told to warm up your car before driving. That's just a myth born of the need for comfort, according to Tom and Ray Magliozzi, better know as CLick and Clack, hosts of the radio talk show Car Talk.

"The engine warms up most efficiently while it's being driven, not while it's idling," says Ray. So start it up and drive slowly until you feel heat coming out o fthe vents. Then you can take it up to normal speed.

"If it's bitter cold out or the car stalls when you put it in drive, then you can wamr it up for a minute or so," adds Tom. "Any longer is a waste of time and gas, and probably an affront to your still-sleeping neighbors."


http://theculvers.net/000264.html

[Nametag]

On frosty mornings, it's impossible to drive safely until the engine has warmed up enough for the heater to keep the windshield clear. At around freezing temps (a really cold California morning), this takes a couple of minutes, which I spend scraping ice or wiping dew off the windows, whichever side of freezing it's on.

[godzillatemple]

I think it depends on the type of engine. My car is turbo-charged, and I've been told repeatedly by just about everybody (including the owner's manual) that it is very important to let the car warm up before engaging the turbo. otherwise, the turbo's bearings may not get sufficient oil. Since the turbo kicks in at about 2000 RPM, it's difficult to just drive slowly without the turbo kicking in.

Barry

[RealityChuck]

Originally posted by The Calculus of Logic
Is there any antidotal evidence ... ?

You fool! You fell into my trap! Do as I bid or you will never get the antidote!! Bwaa-ha-ha-ha-ha-ha-ha!

[handy]

As godzillatemple, mentioned it's very important to read your car manual about this. I haven't found one yet that doesn't tell you what to do about this, The Calculus of Logic. What does YOUR car manual say?