How bad is idling?

[BigBuck]

Is idling bad for the engine? Ive heard different things, some saying your engine is meant to handle it, while others say it's horrible for your car.

That being said, I sometimes let my car idle for extended periods of time when I'm in it with a couple buddies. I am getting ready to change my oil before winter. I am putting in QS UD 5w30 and a P1 filter that will probably run for about 6 to 7 thousand miles. My car doesn't burn or leak a drop of oil. She is good to me.

Are there any oils or filters which could handle extended idling better than others or are modern day quality oils all up to the task?

Thanks,
Mike

 

[The motor guy]

Just as long as the engine doesn't over heat. It's ok. Just adjust your oci accordingly. It's not bad for the engine but your still putting wear on the engine that doesn't show up on the odometer. Good extended drain type oil would be amsoil. And also there EAO filters too are extended drain.

 

[Kuato]

Idling's not bad for the engine, but as m-o-m said it doesn't get counted for your oil change interval.

 

[kkreit01]

As a follow-up on the same topic:

Would it be better to idle, or frequent start and stops? The wife sits in a long line to pick up kids from school. The line often moves every few minutes. Would it be best to idle, or start and stop in these situations? She drives the Hemi, so it kills MPG to idle. I told her to turn it off if it's for 2-3 minutes. Is this worse?

 

[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.

Quote:

but as m-o-m said it doesn't get counted for your oil change interval.

It does if the OLM is smart enough.

 

[SteveSRT8]

it's never going to hurt a healthy late model car that is unmodified.

I have sat in my Silverados for extended periods, and watched as the idle was actually raised to keep the voltage in the correct range because all the accessories such as AC and electric fans were running full blast.

But this is not a blanket statement that applies to all cars.

 

[cbear]

I prefer to leave it run, with the thought of not starting an engine without any oil pressure. Even if that's not true, you are adding wear on your starter and taxing the battery. Starting a car is the most demanding load on your battery.

 

[KrisZ]

I don't think idling is bad, for the engine per say, but at idle the combustion is not optimal and creates more by-products and soot. This leads to stuck rings, clogged EGR's and fuel dilution, which can be bad.

Repeated starting is not bad for the engine at all, provided it is already fully warmed up and it's not cold enough for the oil temp to drop drastically during off time. But all the starts will wear out the starter, battery and possibly the alternator. Doing this several timesduring the day, five times a week would be brutal on the starter, I would just keep on idling.

 

[IndyIan]

Originally Posted By: kkreit01
As a follow-up on the same topic:

Would it be better to idle, or frequent start and stops? The wife sits in a long line to pick up kids from school. The line often moves every few minutes. Would it be best to idle, or start and stop in these situations? She drives the Hemi, so it kills MPG to idle. I told her to turn it off if it's for 2-3 minutes. Is this worse?

Off Topic - Can't your wife or kids walk? I guess parking the car and walking to the door of the school isn't an option?

On Topic - I think frequent hot restarts doesn't create extra wear other than on the starter. Restarting for 10 seconds every couple minutes will save gas for sure.

 

[Colt45ws]

Ford says an hour of idling is worth 33 miles of driving.

 

[Y_K]

carbon build-up if it is excessive

 

[rslifkin]

Idling is bad, as it causes some fuel dilution of the oil, slightly faster ring wear, as well as carbon buildup. Some engines have issues with not enough oil flow to the top end as well. Raising the idle speed to 1200 rpm or so if idling for a long time helps these issues a lot.

 

[BigCahuna]

If an engine has the proper amount of oil in it, can get 10 lbs of oil pressure at idle, is under no load, and the cars computerized fuel injection is feeding it the correct amount of fuel for the speed its running, where do you think all this wear is going to come from? That's the easiest use a motor will ever see.,,

 

[mechtech2]

Doesn't that hemi have a selective cylinder strategy? It should make low demand situations use less fuel .

Anyway, idling used to be worse for cars.
Why?
Carburetors.
They mixed the fuel and air, and THEN it had to be distributed in different sized runners in the intake manifold to the engine's various cylinders.
This resulted in less than perfect distribution, with all cylinders not getting exactly the same mixture. The car was tuned for the leanest cyl, with some always running too rich.

TBI systems had many of the same problems as a carb set up.

But most cars have port fuel injection now, and also very importantly have feedback systems for fuel control[02 feedback].

Idling is still not good for fuel use, but is much better than before. Also note how many cop cars sit and idle.

 

[rslifkin]

BigCahuna - The reason for wear is that at idle, combustion temps are lower, causing some fuel not to burn completely, resulting in fuel washing down the cylinder walls. This doesn't happen to nearly the same level with fuel injected engines as it does with a carb, but it happens.

Also, splash lube up to the rings on engines without piston oil squirters is less at lower rpm. At 1000 - 1200 rpm, this happens better, and combustion temps are kept up better. There's a reason many big diesels have high idle switches. Some cop cars have them too.

Plus, if you look at the vehicle as a whole, if it's idling while being used for something, raising it to a high idle improves alternator output as well.

I've seen engines that were mostly short-tripped and allowed to idle in the cold, and there was enough gas in the oil that the dipstick just smelled like gas.

 

[lexus114]

Originally Posted By: mechtech2
Doesn't that hemi have a selective cylinder strategy? It should make low demand situations use less fuel .

Anyway, idling used to be worse for cars.
Why?
Carburetors.
They mixed the fuel and air, and THEN it had to be distributed in different sized runners in the intake manifold to the engine's various cylinders.
This resulted in less than perfect distribution, with all cylinders not getting exactly the same mixture. The car was tuned for the leanest cyl, with some always running too rich.

TBI systems had many of the same problems as a carb set up.

But most cars have port fuel injection now, and also very importantly have feedback systems for fuel control[02 feedback].

Idling is still not good for fuel use, but is much better than before. Also note how many cop cars sit and idle.


That`s true, but they also get the [censored] blown out of them too.

 

[Rand]

For the most part the engine will outlast the rest of the car.
Some idling isnt that bad..

the worst is remote starting.. and having it idle for 15mins barely warming up when its -10 outside.

yet you dont really see those engines self destructing either.

I generally turn off the engine if its going to me more than 2-3min and the car is warmed up.

 

[M1Accord]

Originally Posted By: kkreit01
As a follow-up on the same topic:

Would it be better to idle, or frequent start and stops? The wife sits in a long line to pick up kids from school. The line often moves every few minutes. Would it be best to idle, or start and stop in these situations? She drives the Hemi, so it kills MPG to idle. I told her to turn it off if it's for 2-3 minutes. Is this worse?


How about parking that thing and wait for your kid(s) the right way, with open arms and at the front door. She may get some exercise out of it instead just risking a fender bender. Either I or my mom picks my sister up from school every day and we would just park the SUV or van and stand in front of the door like half of the parents. The other half is chilling in their SUV or Hemi and make their kid(s) walk to them, crossing the driving path of buses and other parents' vehicle.

 

[casperfun]

I get paranoid idling too at times. But heres my 2 cents. Back when consumer reports did oil comparisons on taxis in new york, they said there was no difference on what type of oil and not alot of wear in the taxis. Maybe people read it here, so knowing taxis idle alot and these vehicles showed good protection during this study. I guess as long as you do your oil changes, idling is not bad just BAD for gas mileage.

 

[kkreit01]

So what I'm reading is idling and starting/stopping can both be bad, but not that bad. I pretty much told the wifey if she's sitting for ~3 minutes, to turn it off. Of course in the winter, she'll be idling. If it were me, I'd go 2 min before school is out, park in the parking lot, and walk to pick up the kids by the door. She prefers to sit in line for 25-30 minutes. The Hemi pretty much gets 13.5 --> 14.5 MPG in town no matter how we drive. It definitely gets the carbon blown out when I drive it on the weekends.

I didn't mean to hijack BigBuck's thread, but I thought I'd piggy-back off it -- rather than starting a new one.