Warming up an automobile

[hovermn]

I used to work with someone at Target while working on overnights. After punching out to go home, she'd hop in her car, start it, then walk back into the building. A squad car drove by, saw this, and gave her a warning. Said that next time she'd get a ticket. This was in West St. Paul.

[Bearfan1963]

In extreme cold I turn my headlights on for 15-30 seconds prior to starting and have never been stranded. Been doing this for the last 20 years after car wouldn't start on a very cold day and someone told me about the headlight trick. Maybe just a coincidence, but I'll keep doing it till it doesn't work.

[Scott M]

Sounds like we need an electrical engineer to make a judgment here.

[shizzy]

if you have a good battery you wouldnt need to turn on your headlights to have enough battery to start the car.

If you didnt have a good battery, is the car going to start at 5 below anyways?? I think not.

if its going to be that cold I yank the battery and bring it inside for the night. Toasty warm battery when its 15 below means I get to work on time......

[Surface Tension]

If turning your headlights on gives the battery a little boost, then theoretically cranking your engine over will do the same.

Wouldn't logic say save that capacity to turn the engine over.

[Scott Stein]

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.

i bent my key slightly so when i start it you can pull the key out of the ignition,leave it run and lock the doors

[upnorth]

The theory I have heard that the lights draw just enough juice to warm the battery a little. That being said I think it bunk, a battery holds only so much juice and I would rather save it to turn the motor over.

[pinkfloyd4ever]

Originally Posted By: airjer

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.

i bent my key slightly so when i start it you can pull the key out of the ignition,leave it run and lock the doors

I am pretty sure it is a city law in Mpls that you can't leave car running unattended

[Jeremy airjer W]

Maplewood and St. Paul are the same!

[Scott K]

I can do it at my house

[theoilman]

I am an Electrical Engineer by education (BSEE Virginia Tech, 1970). I made the original statement in this thread about using the head lights for 30 seconds with a good battery to warm the battery and give extra cranking, and I stand by it.

[LwnmwnMan2]

I let my diesel warm up for about 30 seconds before leaving.

If there's 5" of snow on the ground, and I've overslept, I'm already in reverse while cranking.

[Scott K]

Ford tells you 5 minute max idle time, anytime! Diesels

[jltimm]

Ford tells you 5 minute max idle time, anytime! Diesels

That's if they start!

[Jeremy airjer W]

Ford tells you 5 minute max idle time, anytime! Diesels

That's if they start!

Yup, he just went there!!

[harvey lee]

I will let mine warm up for approx 5-10 minutes on the colder days. On real cold days I also like to let the tranny fluid warn up and flow a bit.

[harvey lee]

I will let mine warm up for approx 5-10 minutes on the colder days.

[Scott M]

I am an Electrical Engineer by education (BSEE Virginia Tech, 1970). I made the original statement in this thread about using the head lights for 30 seconds with a good battery to warm the battery and give extra cranking, and I stand by it.

Works for me Don. Back to back ACC football champion Hokies!

[SkunkedAgain]

Most "experts" say that you don't need to let it warm up more than 15-20 seconds on a cold day. On the really cold days probably not longer than a minute. The real risk is running your motor too hard when the oil isn't fluid enough to lubricate properly. When you start hitting the goop-points that Don mentioned, you want to get the oil sloshing around a bit before moving.

Driving slowly after a minute or two won't harm your vehicle. Fast starts will hurt it in the beginning, but once the engine is partially warmed it's fine.

The reality is that the fuel isn't burning at it most efficient peak until the vehicle hits that 190-205 degree normal operating temperature. So you get worse fuel mileage. The worst fuel mileage is at idle.

IMO, and from everything that I've heard and read, any warming after 30-60 seconds is purely just to make it more comfortable for the driver. You aren't saving any parts from failure unless you plan to gun it out of the driveway. Even then you haven't given the transmission an opportunity to warm up.

So warm up the oil a little and then drive slow.

[federline]

So its pretty cut n dried for engines. I want to hear about transmissions. Thats what makes the most noise after that one-minute warm up until its warmed up! Transmission, transfer case, front diffs, they all sing nice for 5 or 10 miles on a brisk -20 day!

[Whoaru99]

Well, I think you're going to have a long wait for diffs and transfer cases to warm up without driving. Auto trans with cooler in rad will warm up a bit quicker, but still going to take a while.

[Whoaru99]

All in all, I think it's really not that hard of a question.

You start it up, let it warm up for a minute or two, then drive off. I can tell when things start to loosen up and then I feel better about picking up the pace.

Although, I think it's a bit easier in a small town to take it easy for a while vs. in city traffic. If I had to get right out on the highway in traffic, I'd probably let it warm up a bit more.

[Jeremy airjer W]

Or you could jump out on the freeway in rush hour and never see you speedo needle move past 5MPH!

[jwhjr]

Or you could jump out on the freeway in rush hour and never see you speedo needle move past 5MPH!

Especially the way it's gone the last week or so... As far as warming up the transmission goes, I've noticed that on my truck it holds gear longer when its cold. It does this to get the transmission heated up more quickly, and when its warmed up it shifts normally.

[Jeremy airjer W]

My new Tundra will not go into overdrive until the trans temp needle is past the 1/3 mark.