How bad is idling?

[Cyprs]

Driving conditions play big part, for example I live 600 ft off the #1 Trans Canada Highway with 80 mph traffic. In -45F I have no problem idling before putting a load on that car. If is is -45F and I have to stop for 5 minutes I keep it running. If it is 100F in summer I will still idle some to have some warmth in engine before accerlerating on the highway. Once on highway after a respectable driveoff the oil gets plenty heat above 160F out of high wear metal zone in 20 minutes and the oil gets cleaned up good. Fuel injection is a far cry from old slobbering carbs too.

It is common sence and applying it to conditions. If I lived in my small town near by with 20 mph traffic then a longer idle is not needed, the car is basically idling at a slow crawl anyway. On the Highway I drive the far extreme shoulder to drive slow too and when the road is not too busy then this will reduce idle too. I prefer to idle than hard load a cold engine with cold oil,. Once one drives a vehicle long enough you can feel when it is ready to drive off from idle. I dont like uneeded dry starts when waiting either as someone else pointed out too.

Cyprs

 

[antonmnster]

I'd avoid idling it to warm up. It will warm up v e r y slowly and spend much more time in the temp zone where it's making condensation without being able to evaporate it.

But once it's warm, it's up to you. At work, we idle our F350s for up to 48-72 hours. They are happy to do so. It can be rather smelly to floor it after an entire shift of idling, but that's about the worst of it. All modern police cars idle the entire time.

The only issue with excessive idling, once again provided that the engine is warm, is economy. We're idling that much at work because we have periods where we need 24 hour coverage in the winter and the truck is the only shelter at a worksite; we're idling to stay warm. If you're otherwise comfortable, just start and stop the engine as necessary.

The days of carbs are long gone. Just look at any hybrid - they start and stop and run long OCIs. Engine management technology has rendered most of the problems moot.

 

[Y_K]

Originally Posted By: mechtech2
Also note how many cop cars sit and idle.
True. Although P71 idle is > 1200 rpm

 

[Steve S]

Not really worth worrying about. The car is a tool and use it.

 

[Texan4Life]

I idle all the time with the car in my sig and don't think twice. Even for hours sleeping a rest stop when traveling for my job.

 

[Kuato]

Originally Posted By: Quattro Pete
Originally Posted By: fredjacksonsan
Idling's not bad for the engine,

Some say it's bad because at such low rpm there isn't enough oil pressure to properly lubricate the engine. I suppose it depends on the specific engine design though.


Possibly true; however in Bob's "Oil 101" class, it's noted that at lower rpms, lower oil pressure is required. I'd hope that the engine manufacturers designed the oil pump to send sufficient oil at idle, and more with increased rpms, than the other way around!


Originally Posted By: Quattro Pete

It does if the OLM is smart enough.


LOL, I didn't even consider the high tech oil monitoring!

 

[demarpaint]

Originally Posted By: fredjacksonsan
Originally Posted By: Quattro Pete
Originally Posted By: fredjacksonsan
Idling's not bad for the engine,

Some say it's bad because at such low rpm there isn't enough oil pressure to properly lubricate the engine. I suppose it depends on the specific engine design though.


Possibly true; however in Bob's "Oil 101" class, it's noted that at lower rpms, lower oil pressure is required. I'd hope that the engine manufacturers designed the oil pump to send sufficient oil at idle, and more with increased rpms, than the other way around!


Originally Posted By: Quattro Pete

It does if the OLM is smart enough.


LOL, I didn't even consider the high tech oil monitoring!


If they oil pump wasn't pumping enough oil at idle, NYC commuters wouldn't make it home from work 5 days a week. They'd be seizing up their engines.

Idling increases wear, dirt, and combustion bi-products w/o actually driving.

 

[chevrofreak]

Originally Posted By: Y_K
Originally Posted By: mechtech2
Also note how many cop cars sit and idle.
True. Although P71 idle is > 1200 rpm


Mine idles at roughly 800rpm when warm, and 1150 on cold startup, then drops soon after.

 

[A_Harman]

The biggest concern with idling is cam and lifter wear. Back during the carburetor and flat-tappet cam era, the most severe wear test that GM did was called the "Taxi Test". This was just extended idling with oil that was not warm enough to drive off the condensation and unburned fuel. At idle, valve spring loads cause high contact stresses near peak lift, and there is not enough centrifugal force to reduce it. So the cam lobe and lifter are forced together into boundary lubrication conditions, possibly leading to metal-to-metal contact. This is why oil used to have higher concentration of ZDDP.

Modern fuel-injected engines with roller-tappet cams do not have this problem, so they are safe to idle. But why waste the fuel? I read recently in an article about hybrid cars that if the engine can be shut down for at least 7 seconds, there would be a net savings of fuel.

 

[demarpaint]

Originally Posted By: A_Harman

Modern fuel-injected engines with roller-tappet cams do not have this problem, so they are safe to idle. But why waste the fuel? I read recently in an article about hybrid cars that if the engine can be shut down for at least 7 seconds, there would be a net savings of fuel.


I agree, but see Hydrid cars having problems as well. The oil will hardly ever get up to operating temps, and that creates all kinds of wear issues. JMO

 

[Boss302fan]

All it does is suck gas. I would only let it idle in normal driving conditions. Never at home for more then a minute or so...

 

[uart]

Originally Posted By: Texan4Life
I idle all the time with the car in my sig and don't think twice. Even for hours sleeping a rest stop when traveling for my job.


In Texas?

I could understand that in Alaska or Canada where you need heat, but why in Texas. Is it so you can run the A/C?

 

[A_Harman]

Originally Posted By: Texan4Life
I idle all the time with the car in my sig and don't think twice. Even for hours sleeping a rest stop when traveling for my job.


It's good you're using a heavy-duty oil!

 

[countryboy9799]

I think if you need to there is no problem idleing but if you can shut if off to save fuel. I think the no oil at startup is not a factor worth worrying about. The engine will outlast the car under most circumstances.
I work for a trucking company that makes regional deliveries with 20 deliveries a day. The trucks are started 50 plus times a day with little warm up and they now have computers in to track the idle time per driver so you really have to watch it. It's taken a lot of getting used to but times are changing.

 

[Texan4Life]

Originally Posted By: uart
Originally Posted By: Texan4Life
I idle all the time with the car in my sig and don't think twice. Even for hours sleeping a rest stop when traveling for my job.


In Texas?

I could understand that in Alaska or Canada where you need heat, but why in Texas. Is it so you can run the A/C?


You bet your bippy! ...its hot down here


::edit::

this makes me want to do an experiment. go say 5k miles take a used oil analysis (without changing oil) then idle say 5 or 10 hours straight and take another used oil analysis.

 

[Kuato]

Originally Posted By: Texan4Life


this makes me want to do an experiment. go say 5k miles take a used oil analysis (without changing oil) then idle say 5 or 10 hours straight and take another used oil analysis.



VERRRRRY interesting thought!! I may have to try that on my next oil change in 2800 miles.

 

[Brons2]

I don't see the danger inherent in hot restarts that some posters have alluded to. Wear on battery and starter?? My car restarts almost instantaneously when I shut it off to avoid extended idling. Which, I always do even though it's a bit uncomfortable when it's 100F outside.

My used oil analysis has never shown excessive wear from this. I have a number of them posted.

 

[Tahoe4Life]

Originally Posted By: Brons2
I don't see the danger inherent in hot restarts that some posters have alluded to. Wear on battery and starter?? My car restarts almost instantaneously when I shut it off to avoid extended idling. Which, I always do even though it's a bit uncomfortable when it's 100F outside.


Shutting the car off for a very short period does not make any sense to me especially in the hot summer or cold winter. No sense at all.

 

[Steve S]

Originally Posted By: Brons2
I don't see the danger inherent in hot restarts that some posters have alluded to. Wear on battery and starter?? My car restarts almost instantaneously when I shut it off to avoid extended idling. Which, I always do even though it's a bit uncomfortable when it's 100F outside.

My used oil analysis has never shown excessive wear from this. I have a number of them posted.
The starter wears every time it is used. I have rebuilt many. The greatest wear is on the eletrical contact points in the solenoid ,lots of amps.

 

[Ryan]

Working as a Deputy Sheriff I will have to let my car idle for quite some time depending on what is going on. If I have to block off a road and let it idle for an hour, when I get back in and drive off, it is all good. You would have to idle your car for hours and hours to see noticeable problems. For example, I used to work for the Secret Service. Working around the White House, we had Crown Vics set up at different areas and you just sat in the car while on that rotation and get out if you need to stop a truck coming at you. These cars would idle for about 16 hours a day. I remember hearing water gurgling in the mufflers. You would see some people rev it up and water would pour out and a big puff of smoke would pile out. The one time I had a truck roll right past me one day, I actually had to put the car in drive and try to stop it. The car stuttered and almost cut off. They would also overheat in the summer after idling for so long.