Eric L.

A few days ago I ran across the "should I warm up the car" thread. This week, Cartalk (with Tom and Ray) posted a similar question, albeit a bit more interesting.

Here is a reprint of the question. I hope I'm not violating some sort of copyright by posting it here instead of providing a link. The link is updated frequently and the question will not be there be anymore, so I am posting the text instead.

Dear Tom and Ray:


I have a troubling situation to ask you about. Three times in the past several months, my wife has parked her car, gotten out and absent-mindedly left this '99 Mazda 626 running. Once, she left it running all day at her office. My first question is, what kind of damage can this do? And the obvious second question is, why is she doing this, and how can I stop her? -- JR

Ray: Well, to answer your first question, leaving the car running all day won't do any damage. As long as the engine's cooling system is working normally, a modern car can run for days and days -- until it runs out of gas -- without causing itself any harm.

Tom: Think about it, JR. If long-term idling caused engine damage, wouldn't you see thousands of broken-down police cars in Dunkin Donuts parking lots?

Ray: The second question is trickier. I'd have to assume that she's not used to a car that's so smooth and quiet. What was her previous car? Was it a 1986 Chevy Cavalier with a bad muffler? My guess is that the signals she used to get from her old car -- the noises and vibrations that told her it was running -- are not there in her new car. You might need to loosen up the fan belt and get this Mazda squealing.

Tom: Still, a person has to be distracted in some way to forget to turn off his or her engine. So something must have distracted her on those days. Maybe it's Bob, the hot new guy from marketing?

Ray: Here are my suggestions: First, if she hasn't already, she should stash an extra set of keys at work. That might not help her remember, but it'll save you the trips to go rescue her. Then I'd get her one of those retractable key holders that you can clip onto your belt.

Tom: If she puts the car key on that and clips the thing to her clothing, and then tries to get out of the car with the key still in the ignition, she'll rip off whatever she's wearing and be so embarrassed that she'll never forget again.

Ray: No, it'll just give her a friendly reminder that she "forgot something." She can even clip it to her pocketbook if she's good at remembering that. And don't be too hard on her, JR. She's obviously got more important things on her mind. And in the grand scheme of things, this is not a big deal.

Eric L.

So it looks like Tom and Ray's opinion is that idling is not bad for the car, and will not cause insufficient oil pressure and poor lubrication to the valvetrain. I would tend to agree.

AznWontonboy

Idling just puts more unverified miles on the car IMO. The pistons are still moving up and down, friction=wear and tear. Not like its some major damage, but you get what I'm saying. I think

iwannabmw

iTrader: (3)

The engine should tend to run richer when just idling, which can lead to fuel seeping past the rings, diluting the oil and causing it to become contaminated sooner. The richer mixture combined with lower operating temps. can lead to more deposits on the valves and spark plugs causing loss of power, hesitation and idle roughness as well. Police cars and taxi's, which see lot's of idle time are on a very severe maintenance schedule to help combat some of these issues.

Will it kill the car to leave it running, no. Will lead to problems, yes, if not taken care of.

lp

iTrader: (1)

A coolant leak might make her remember. I've read before that well off Saudis leave their Mercs etc idling for hours while away just to keep the A/C running.

95emeraldgxe

good or bad, i'd kill my wife(if i had one) if she left my car running all day!!!!

Frank Fontaine

I agree with you, idling is not gonna harm the motor. It's just not that delicate. The carpet cleaner who came to my house yesterday left his van idling for 1 1/2 hours--the pressure machine runs off of a driveshaft from the motor. So to put things in light, his van will be idling about 8-10 hours every work day.

Our question on the forum I believe was more about warming up, which is totally unnecessary and of no benefit. The only benefit is to have heat in the car, but wasteful. Just don't start her up cold and gun the motor. Shift at about 2300-2500 when the motor is cold and it'll be just fine.