Is idling hard on motor oil? If so - then why?

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Originally Posted By: OVERK1LL
Originally Posted By: XS650
1985 isn't old. I have socks that old.


That scares me
grin2.gif


They have been washed.
 
Originally Posted By: XS650
Originally Posted By: OVERK1LL
Originally Posted By: XS650
1985 isn't old. I have socks that old.


That scares me
grin2.gif


They have been washed.


But they are not worn out? Are they special occasion socks?
wink.gif
 
Originally Posted By: XS650
Originally Posted By: ekpolk
Idling? What's idling?



Posting on a forum is the best definition I can come up with right now.
grin2.gif



True -- I idle -- but my car doesn't!
wink.gif
 
Originally Posted By: StevieC
Originally Posted By: alphasparky353
So if idling with ac on, with fan going would that help keep temps down?


No because the engine is under excess load. I have monitored my coolant temperature with my Scan gauge both with the A/C on and off and it runs about 10 degrees hotter with the A/C running in traffic.
wink.gif

Air con would be counterproductive in trying to cool the engine. Now if you ran the heater, it would help cool the engine.
 
Originally Posted By: TallPaul
Air con would be counterproductive in trying to cool the engine. Now if you ran the heater, it would help cool the engine.


Don't most vehicles these days ALWAYS have the heater online?

When you "turn on" the heater all you are doing is opening a door to the core?

So you are getting all the coolant in the system working...
 
A/C's affect on engine cooling is largely dependent on engine size. A 150hp gas 4cyl car will have a different response than a 350hp Diesel in a pickup.

With vehicles that have viscus fan drives, the air temp across the fan clutch is the only thing that makes it turn on. For those with electric or electro-viscus fan drives many things can turn the fan on. Fan operating also has affect on A/C operation, not because of engine load by itself. The fan is commanded on at no/low road speed because if there is no airflow across the A/C condenser you get very little cabin cooling.

The A/C condenser is usually the first cooler placed in the stack, so an increase in coolant temps at no/low road speeds is largely due to more heat in the cooling air across the radiator.

Idling is not good, but on an engine at operating temp is of little concern with modern engines. The cooling systems, engine design, materials and machine work on modern engines are all much better than at any other time. With electronic engine controls many aspect of the engine are closely monitored and controlled. Idling is most harmful on a cold engine as even with EFI the fuel mixture must be rich enough to keep the engine running.
 
Originally Posted By: TallPaul
...Air con would be counterproductive in trying to cool the engine. Now if you ran the heater, it would help cool the engine.


Well, since there are now so many of us around, I'll offer the "alternate hybrid answer": In these cars, you should run the AC in all but the coldest conditions*, and not running the AC will ultimately put more stress on the entire system, likely causing the ICE to run hotter than normal, thus stressing the oil more than normal.

Why? These cars make clever "double use" of conditioned air. The traction battery is cooled almost totally by "used" passenger cabin air, drawn by fan through an intake vent in the rear of the cabin. If you try to "save energy" by not using the AC and sweating it out, the battery temp will rise. Once batt temp hits a certain level, the ECU will start to "protect" it by allowing less storage and less draw in an attempt to control and reverse the rising temps.

The end result, again, will be that the ECU will force the ICE to do most (or all) of the work, putting more stress on the ICE, and probably it's oil.

* The best way to handle this is to just leave the system in "auto" and set the temp you want. The AC is all electric, and the computer will run the variable speed compressor only as needed.
 
I remember about 25 years ago an automotive journalist remarked in a review of the Honda Accord that it was the only car he ever tested that could idle indefinitely without overheating. Most cars can do that these days.
 
With modern cars running in feedback mode even at idle and watching my AF on the dyno, I now know that the AF is the same at idle and cruise. I can't see how fuel dilution is even a consideration.

As for oil temps, they seem to be more dependant on engine load. *If* the coolant goes up a few degrees at idle (my TL and GN don't but my rental cobalt did) oil temp should still be the same or lower than cruise because there's very little load.

I think the worst oil related thing you're going to get from an idling engine is unaccounted for run time when calculating your OCI.
 
what r these "Scan gauges" u guys r talking about? to read the coolant temp? odb2? where can i find one? what brand?

thanks
 
Originally Posted By: madamd
what r these "Scan gauges" u guys r talking about? to read the coolant temp? odb2? where can i find one? what brand?

thanks


And here's what mine looks like as installed in my Camry Hybrid. There are hundreds of parameters you can choose to display, and obviously thousands of combined possibilities. You can also read diagnostic codes (though I have yet to see one -- knock on wood).

Scan-Gauge--10-23-08%20016-v2snr.jpg
 
Originally Posted By: OVERK1LL
Originally Posted By: Chris142
The old pushrod V8's (and v6's too I guess) would eat cams if idled too much. The cams were lubed from oil thrown off the rods and at an idle not much oil got thrown.


What?

There were many roller pushrod V8's, the SBF went roller in the Mustang in 1985.....

Oil is pressure-fed to the lifters, which regulate oil flow to the top-end. Oil coming down the lifter bores lubricates the camshaft lobes, the camshaft bearings are pressure-fed.


I'm talking non roller engines. This is why you break in a new cam @2000 rpm.

http://www.4secondsflat.com/Hydraulic_lifter_cams.html

"Because the camshaft and lifters are primarily lubricated by the splash of oil from the crankshaft, any RPM below 1,800 may result in insufficient lubrication and may cause cam lobe failure."
 
I like the blue display in your dash Ekpolk, I was thinking of changing all my dash lights to blue LED's in my Silverado, it looks so much better!
 
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Originally Posted By: ekpolk
Originally Posted By: TallPaul
...Air con would be counterproductive in trying to cool the engine. Now if you ran the heater, it would help cool the engine.


Well, since there are now so many of us around, I'll offer the "alternate hybrid answer": In these cars, you should run the AC in all but the coldest conditions*, and not running the AC will ultimately put more stress on the entire system, likely causing the ICE to run hotter than normal, thus stressing the oil more than normal.

Why? These cars make clever "double use" of conditioned air. The traction battery is cooled almost totally by "used" passenger cabin air, drawn by fan through an intake vent in the rear of the cabin. If you try to "save energy" by not using the AC and sweating it out, the battery temp will rise. Once batt temp hits a certain level, the ECU will start to "protect" it by allowing less storage and less draw in an attempt to control and reverse the rising temps.

The end result, again, will be that the ECU will force the ICE to do most (or all) of the work, putting more stress on the ICE, and probably it's oil.

* The best way to handle this is to just leave the system in "auto" and set the temp you want. The AC is all electric, and the computer will run the variable speed compressor only as needed.


Thats exactly what we do with our entire fleet...We just leave the A/C on automatic and set the temp to whatever and forget it...We never ever shut it off...We have been doing that since the early 70's.

BTW you will also save allot of money by not changing out your window regulators as you won't be playing with your windows every time you get into your car.

As far as idling goes if it was that bad the cars down here would be dropping like flies in this jungle heat...The K-9 cars idle for hours every day with the a/c on plus allot of the taxis are Grand Marquis without any sort of police package and they are doing just fine...I see some Grand Marquis taxis that are at least 10 years old and they run all day in traffic with the a/c on...The driver of one of those told me he changes out his oil every 5K miles using 5w20 full synthetic motorcraft.
 
Idling is good. It beats a stalled engine.
If you have to idle, then let it idle.
I would not go out of my way to idle an engine.
Modern FI engines are very good about this.
Some cop cars and emergency vehicles idle for prolonged periods.
 
A couple of comments:

Whether the AC helps or hinders in cooling depends on the car.

My vehicle has a viscous main fan AND an electric auxiliary fan. Different revisions of my vehicle during its model run had different variants of the electric system (2 speed, 3 speed, PWM variable speed) but the principles are the same. The viscous system works like any other, the temperature/heating capacity of the air behind the rad determines when it kicks in.

If PWM, the auxiliary is controlled exclusively by the DME based on many factors. If multi-speed, it is controlled by a dual temperature switch in the side of the rad (to control engine temps if the main fan is inoperative, failed or incapable of handling the heat) and the AC system (runs on low whenever the AC is on).

In weather ranging from "nice" to hot with the AC off, the main fan will kick in every time you stop sounding obviously engaged when you pull away from the stop sign, traffic signal, drive through, whatever. In cool to cold ambient temps, the main fan never engages fully. In all but the hottest weather, running the AC (thus engaging the electric fan at low speed) will prevent the main fan from engaging.

I am also able to display the head coolant temperature digitally on my instrument cluster when in a diagnostic mode. With the AC on, it will usually sit at or very near the thermostat control temperature. With the AC off, it very clearly elevates several degrees during idle.

I'm sure many, many vehicles run an electric fan at some speed whenever the AC is on. Any vehicles that operate in this fashion would probably show more stable coolant temperatures in hot conditions with the AC on, despite the extra thermal load and work load on the systems.

If you really want to punish things, idle with the AC off in the heat. Frankly, this should probably be done from time-to-time as a test to make sure your vehicle is working as it should, instead of suffering a failure at a time that is not by choice. If you cannot display accurate, unbuffered temperature readouts on your dash or something like a scangauge, you can read rad hose temps with an IR thermometer.


On idling unrelated to cooling. Is idling hard on the oil? Maybe not, other than heat loading under the hood goes up so it may start to cook or at least it will get even thinner. With the low pump speed/oil pressure at idle, excessive additional thickening is even more of a factor. Idling may or may not affect your oil, but it is harder on the engine itself.

Those referencing ambulances and other emergency response vehicles. I'd be pretty certain that specialized industrial engines like those in fire trucks are probably made to oil properly at idle, and probably have larger cooling systems meant to operate at idle. The same is probably true of any equipment that uses the main engine to drive hydraulic systems like bucket-lifts - the engineers know how they're going to be used and it's part of the design. I wouldn't even be surprised if police interceptors, or perhaps the entire model line they're based on, wouldn't have higher volume or higher speed oil pumps to deliver more oil volume/pressure at idle.

I wouldn't be declaring that a Toyota Yaris must be able to idle indefinitely because a police car or taxi (same model line) can.
 
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I thought the police interceptor's had an auto idle-up feature that increased the idle speed a couple hundred rpm's when the motor was under a heavy load at idle due to all emergency lights being on etc. That small increase in rpm's would help increase oil pressure as well.
 
Originally Posted By: xxch4osxx
I like the blue display in your dash Ekpolk, I was thinking of changing all my dash lights to blue LED's in my Silverado, it looks so much better!


My apologies for being OT, but thank you, I agree; it's a nice look. But not so fast, there's a catch. Those blue halos brighten and darken under control of the ECU as an "expression" of the computer's opinion of how efficiently you're driving. When you start up, no halo. I turn 'em blue almost every time, but still. This sort of goofiness could come only from the folks who brought us those delightful 1950s Godzilla movies.
smirk2.gif


EDIT: Oh yeah, the ScanGauge's colors are widely adjustable to match your ambient colors. Notice how I have it almost perfectly matched to the Camry's colors.
 
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Originally Posted By: Chris142
Originally Posted By: OVERK1LL
Originally Posted By: Chris142
The old pushrod V8's (and v6's too I guess) would eat cams if idled too much. The cams were lubed from oil thrown off the rods and at an idle not much oil got thrown.


What?

There were many roller pushrod V8's, the SBF went roller in the Mustang in 1985.....

Oil is pressure-fed to the lifters, which regulate oil flow to the top-end. Oil coming down the lifter bores lubricates the camshaft lobes, the camshaft bearings are pressure-fed.


I'm talking non roller engines. This is why you break in a new cam @2000 rpm.

http://www.4secondsflat.com/Hydraulic_lifter_cams.html

"Because the camshaft and lifters are primarily lubricated by the splash of oil from the crankshaft, any RPM below 1,800 may result in insufficient lubrication and may cause cam lobe failure."


I don't completely agree with that article. That is because the cam is lubricated in two ways.

Many attempts at preventing flat-tappet camshaft failure in race engines have involved slotting the sides of the lifters to allow more oil to get on the lobes; one racing team even went as far as to put a tiny hole in the bottom of the lifter so that pressure-fed oil was put directly on the lobe.

While there IS spray from between the rods and crankshaft; the same oil that is sprayed on the sides of the bores, the camshaft benefits from also being lubed (on the lobes) from the lifter bores as well.

Oil selection, break-in procedure, spring pressure and a host of other things are all relevant to how long a flat-tappet camshaft lives for.

For example, the Ford 302, in flat tappet form, is not known for wiping cam lobes with the stock cam in it. No matter how much it is idled. Same goes for its larger 351 brother.

Situations where one typically does come across people wiping cam lobes is performance builds. Where of course higher spring pressure, more aggressive ramp-rates and potentially sub-par cam core material can all play a role.

In regards to the 2,000RPM thing, it is done for a few reasons:

1. Oil flow. Both spray and from the lifter bores.
2. Lifter rotation. In order to get the lifters to properly "spin" on the lobes, you must have the engine at a moderate RPM during break-in.
 
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