Warming up an automobile

[Scott M]

Allright, the Minnesota dilemma....How long should you warm a car or truck up and in what conditions? I.E. -20 degrees, 0 degrees, 20 degrees, 5 minutes, 2 minutes, don't need to warm it up, etc. Also, in not warming a vehicle up what exactly are you doing to the engine?

[jwhjr]

I start it, pull out of the garage, and go. I have about 5 miles until the highway, so I just take it easy and its usually warmed up to full temp by then.

[hovermn]

I've heard all sorts of things, but have settled on the advice I read in Auto Week. I idle for a minute or so to let the cylinders warm up a bit, then take it nice and slow for a mile or so. After that, It's slow accel. until it's up to temp.

[Shack]

If my car/truck is parked outside in those temps, I warm up for about 5-10 minutes!

I like it warm when I get in

[jwhjr]

If my car/truck is parked outside in those temps, I warm up for about 5-10 minutes!

I like it warm when I get in

When mine's outside up north that's another story, I let it warm up then. 10-15+ below is too cold to drive off in right away

[shizzy]

usually fire up my truck, grab the scraper and start scraping. I hop back in and sit for about another minute then drive off. I also take it easy till I see the temp needle start to move. I find most vehicles warm up faster if you drive it.

[Black_Bay]

I wonder more about how the transmission handles -0 weather at start up.

[pinkfloyd4ever]

I was told in cold weather you never want the first engaged gear to be reverse, so I back in at night. Let it run for a minute then do the same, easy on the acceleration until at its normal running temp

[Jeremy airjer W]

These are interesting!!

[jltimm]

Come on Airjer, what is your opinion?

[titelines]

I never read this anywhere, but have always done it for some reason.

I start it up and let the idle come down to normal before driving off. The time needed for this to happen varies depending on the temperature - the colder it is the longer it takes.

[Scott K]

For me, if the temp is from the teens or above maybe a minute, or until I clean the windows off. If the temps are below 0, I will let it warm maybe 5 minutes at most! Well unless I want the vehicle warm before I leave.

[Jeremy airjer W]

Come on Airjer, what is your opinion?

Wait for it.........Wait for it............

[pinkfloyd4ever]

Originally Posted By: jltimm

Come on Airjer, what is your opinion?

Wait for it.........Wait for it............

he's gonna blow us out of the water on this one, maybe garage is a better word than water

[Black_Bay]

Airjer can't respond because his car broke down after he didn't let it warm up. Kidding

Actually I bet he's going to say you don't need to warm up your car.

[Jeremy airjer W]

Here's the questions I have and don't necessarily have the answers to.

How long does it take for the oil to warm up and flow somewhat normally (conventional oil)?

How long does it take for trans fluid to warm up?

How long does it take for coolant to flow through the radiator?

If the trans cooler is in the radiator and the vehicle is left to idle isn't the trans fluid being circulated through ambient temp (freezing cold) coolant until the t-stat opens?

Don't most Chrysler products not circulate trans fluid in park? And isn't that the reason they need to be checked in neutral?

Since coolant is in direct contact with cylinder walls and the rest of the combustion chamber wouldn't it warm up faster than the oil, which a majority of it sits in the oil pan which is surrounded by ambient temp air until it is pumped through the engine?

What temp is too cold?

I think letting it warm up is a personal convenience to a point. If the vehicle is in top shape with a good battery you will know when the car really struggles to start. IMO, thats a good time to let it warm up. How long? Depends on the vehicle! If theres warm air coming out of the vents than I would say your in good shape. Personally I have had no problems jumping into any one of my vehicles, past or present, starting it, get myself situated, buckled, and take off. Unless we get one of those really cold mornings and I can tell its really struggling to start, Or the windows are all iced up!

[theoilman]

Ok Airjer - some actual technical about the low temperatures.

Engine oil - conventional petroleum, approximately -20 deg F and it is likely a jel - close to jello. Warm the engine at idle at least until oil pressure has stabilized at some kind of a normal range. At -20 deg F conventional oil will likely take 5 minutes or longer.

Engine Oil - AMSOIL 5W-30 or 10W-30 pour points of -55 deg F or lower, less than 1 minute warm up OK to go.

Engine Oil - Other brands of synthetics - typical pour points of around -30 deg or a bit lower; long warmups typically not necessary.

Automatic Transmission - petroleum (Dex III, Mercon) - at -20 deg if driven before warming up many have no shift or very lazy shifts for the first mile or so - it would be a whole lot kinder to the transmission to warm it up 5 minutes or maybe longer (yes, Dodge rear wheel drives need to be in neutral to get normal flows to take advantage of warming up). When this cold you are getting no lube flow, and driving when it won't shift is probably damaging bearings, gears, clutches and more.

Automatic Transmission - Dex VI and Mercon V are synthetic or at least partial synthetic fluids and shouldn't be a problem.

AMSOIL ATF, pour point -65 deg or lower - just go ahead, the transmission should shift and lubricate normally.

Differentials - petroleum gear lubes jel at 0 deg or warmer, but warming up the engine while parked will do nothing. Drive gently the first couple of miles.

Coolant - no problem unless you are below your protection level.

Battery - when very cold it has less cranking power. Many times turning the head lights on for 30 seconds will warm up the battery and it will have much more cranking power. You gain a lot more than you lose operating the lights.

[Jeremy airjer W]

Good info Don!!!

Armed with that knowledge the average person could say 0 and above is for convenience, 0 to -10 can't hurt and below -10 why not.

[Surface Tension]

I was taught many years ago that an engine should be warmed up. That was a time of carburetors with manual and automatic chokes. Today we have fuel injection a mess of sensors and a computer that will take everything into account. Because of that some experts will tell you a warm up is just wasting gas. They miss the point that engine has an optimal operating temp. To put it under load before getting to that temp isn't doing the engine any good.

[Scott M]

Good info guys. I did not know that about turning on your headlights for 30 seconds to get some more cranking power.

[Surface Tension]

I hate to disagree.

Your using up battery capacity by turning you headlights on that otherwise could be starting your car.

If this were a good idea, then when cranking your engine over it would be warming the battery at the same time.

[Scott K]

I hate to disagree.

Your using up battery capacity by turning you headlights on that otherwise could be starting your car.

If this were a good idea, then when cranking your engine over it would be warming the battery at the same time.

If you have a weak battery turning on your headlights will just make it weaker. If you have a good battery, in theory I could see how this would help.

[Jeremy airjer W]

I don't see how a 10 to 15 amp draw (+or-) for 30 seconds is going to affect a battery either.

[zamboni]

When I lived in Kansas City it was illegal to warm car up unattended, and after working in the rental car biz and seeing all the non-returned cars, I see why. Isn't there a law against it in Minneapolis as well??

[Jeremy airjer W]

I'm not sure if its a state or metro deal but the car can not be left unattended with the keys in the ignition and running.