to warm up engine or drive it cold

[XCT]

when i lived in europe, i was always surprised to see the germans get in their mercedes or beemers on a cold morning and start driving away from the curb almost before the engine had fully started!

me on the other hand: i warm up our XC70 for 10-15 minutes in the high altitude mountain mornings until the inside of the car is warm and the ice is melted on the glass.

that's one extreme to the other.

my question: are either habits described above harmful?

[tgrumaj]

OK I confess. My entire life I've just started my car and driven. No warm up not even in the coldest weather. I had an Acura Legand and it got to 236,000 with no problems before I gave it to my son. I now have a 1999XC with 107,000 and the engine parts are about the only things I haven't replaced but nothing related to cold starts.

Here's my qualifiers. I've always used good synthetic oil (Mobile 1) and kept the oil changed every 5-7k miles. I drive in mostly city streets so seldom get the RPMs up (above 2,000) before the car is truly warmed up. I have a light foot on the gas so again the RPMs aren't high. Finally the car is garaged so I seldom get in that the temp. in the garage is below 20 or 25 even if it's 0 outside and at work it's in a basement garage where the temp is seldon below freezing. If I lived in Montreal and kept the car outside day and night I might act differently!!!

My wife is the same and traded in her Mazda 929 (176,000k miles) for an Acura. We've simply never had engine issues on any of our cars so from our experieice driving cold doesn't seem to be an issue.

[gregvet]

I got my 2007 XC70 just this last January. We have had -20 F temps here and I just start and drive without warming up. Like tgrumaj posted, I keep RPM's below 2K until temp indicator is up to normal.

[littlewaywelt]

Tom and Ray on NPR's car talk addressed this recently. Unless you're driving a deisel you don't need to warm up the engine at all. An engine at idle only wastes gas.

However if you have a turbo charged engine you should avoid using the turbo or minimize it's use until the engine has warmed up a little and moved oil into it.

[John@CdnRockies]

"Start-up and drive gently until the engine temp indicator starts moving" has been my motto. My Camry based in Montreal hit 350,000 kilometers on that basis and was still running fine when I traded it in. All of my other cars were in the 250,000+ kilometer range before they were traded and none of them ever had a hint of engine problems.

John

[MoeB]

Don't know that it matters much but I usually warm up all our vehicles for 3 to 5 minutes before driving off, year-round. A tad longer if it's cold.

[tgwillard]

I sometimes will wait until the idle comes down after a cold start on my XC70. I will start my wife's S80 before she heads off to work if it is below freezing, just to begin to warm up the car and rear window defroster. I use synthetic oil in both cars.

[jmoser]

Under most conditions warm up is not necessary. In sub-freezing temps 10 - 30 sec is usually plenty to let the cylinder walls reach temps where the fuel droplets will not condense and dilute the oil. In brutal cold temps near or below zero F I would warm up any engine for at least 30 sec.

For gasoline engines I cannot think of any reason why more than 60 sec would bring any benefit.

I have to differ a bit from the NPR guys - there are legitimate reasons to allow internal temps to stabilize a bit before driving.

You should never drive at highway speeds until the engine reaches rated operating temperature.

[skibo]

My XC is driven by the wife 95% of the time. When it was new, I asked her to wait unit the idle dropped below 1000 before putting the car in gear. I figured she'd long forgotten or disregarded my request, until last week when she mentioned that her coworker/passengers were mocking her a bit for waiting to move. I was impressed that after 27 months she was still doing that.

[Raynald]

"Start-up and drive gently until the engine temp indicator starts moving" has been my motto. (...)Agree with John. The car will warm up even quicker if you can drive gently for 2 or 3 kilometers. Furthermore, it's more environment friendly too! :D

[littlewaywelt]

Don't know that it matters much but I usually warm up all our vehicles for 3 to 5 minutes before driving off, year-round. A tad longer if it's cold.

3-5 mins is probably wasting a fair amount of fuel and putting excess carbon out over the life of the vehicle.

[Jorge-789995]

when i lived in europe, i was always surprised to see the germans get in their mercedes or beemers on a cold morning and start driving away from the curb almost before the engine had fully started!


I thought it was a law in Germany that you couldn't idle your car to warm it up. I lived there 20 years ago, and the Polizei walked up to a coworker one cold morning and told him to drive away as he was sitting there warming up the car.

You are right, though, the Germans always drove off right away, while it was customary to see the Americans sit there for 5 minutes first or scrap the windows while idling.

My current neighbor drives me crazy sometimes by idling their SUV in their driveway for 15-20 minutes some mornings. Once, I noticed it idling for 50-60minutes.

[skibo]

There is always the comfort factor to consider as well. I don't know how common it is elsewhere, but in my area 'remote car starters' are very popular for those who park outside in the winter - just point this thing out the window to your car and when you get in, the heater is blowing warm air - the windows are thawed - the seats are warm - etc. I'm considering getting one this year.

As for the envinronmental aspects, I consider myself pretty green, but I'd guess the fuel needed to idle a car for 5-10 minutes is negligable. I don't have any data to back that up, but I do know that the 4500 HP engines I work on burn 3 gallons of diesel per hour when idling. So doing a simple ratio on power and neglecting any differences in energy capacity between gasoline and diesel, that would say idling an XC for 10 minutes burns........(pulling up the calculator).......3 ounces (0.02 gallons or 0.09 liters) of fuel. That's a pretty rough estimate but it gives a sense of scale.

[Raynald]

You're probably right on the amount of fuel used, but we must consider the nature of pollutant in engine emission. When cold, the engine doesn't burn fuel as efficiently, the catalytic converter doesn't do its job, and so on. When the car rolls, it warms up faster and for the same amount of fuel, we obviously get further than idling with less emission for the same amount of fuel. No wonder why hybrid cars shut off the gas engine when stopping. :)

As for remote starters, Mrs R. has the most advanced and sophisticated system in the world: "Honey, would you go out start the car, pleaaassse?" :D

[Art]

With all this talk about engine emissions, the City of Vancouver's idle-free bylaw now has some bite to it. More here (http://www.city.vancouver.bc.ca/ctyclerk/NewsReleases2007/NRidlefreeenforcement.htm). :)

[jmeljr]

When I start up my XC70 it is always running at 1500 rpm's, and 99% of the time I let it warm up a minute or two until it settles down to 1000 rpm's. I am not sure if that is the turbo warming up or not, just makes me feel better doing that.
When I am in a rush and forget, it always bum's me out as I hear a little thump as the tranny pops into gear and the car moves away at fast idle.

[geo]

hi
Engines will not warm up effectivley on tickover, the length of time it will take for any engine part to reach working temperatue will induce premature bore wear on a petrol (gas) engine. When a diesel starts and runs it is already practically ready for work. Give it a few seconds to fill the torque converter and pressurize the auto transmssion and if you are at the extreme lower end of the temperature scale then drive modestly for the first 5 minutes whereby engine warm up will be quick and relatively damage free. Also all the Transmission and Power steering fluids will be warming and flowing free. If to drive safely you need enough heat to keep the screen clear, now that is another question.
By now you have a rising temp gauge and can drive however you consider normally.
geo

[Willy]

This may have been mentioned before: can't a block heater provide enough warming of the
engine so that driving off right after startup won't hurt anything (I don't think driving off "cold"
is bad, I think it is the best thing to do) and may even provide some warmth to the cabin?
Willy