what is a safe oil op temp ?

[SteveSRT8]

Originally Posted By: dnewton3
I think we need to clarify the question here, or more specifically, understand that there are actually two questions likely being addressed:
1) what is a safe temp for the ISX
2) what is a safe temp for the lube

I don't know enough about the operational parameters set into the PCM for the ISX; someone else will have to help out here.

As for the lube, 250F is in no way unsafe. Even a conventional lube can provide a good performance if the base stock is of good quality. I believe an ideal temp would be 200-225F; most would agree about that. But a little spike in oil temp is not going to grenade the engine nor the lube. Even long sustained runs are tolerable. If you were to approach 300F in the sump, I would be concerned. But not at 250F.

And just for reference, before any of you go off half-cocked and say I'm nuts, I'll offer this bit of information ...
In the infamous GM filter study (881825), they ran the DD-60 engines at full load, with the sump at 250F for the entire duration of all the tests. Eight hours at a time. Repeated several times. On conventional lube from 1988.

And while we also would agree that massive oxidation insolubles are a bad thing, I'll remind you all that some amount of high-heat oxidation is actually a good thing, because it promotes the TCB (tribo chemical boundary layer) formation on the part wear surfaces. Or have you all forgot about SAE 2007-01-4133? This anti-wear layer of oxidation byproduct is actually a good thing, and is bolstered by higher heat. Once it is established, wear rates typically drop precipitously by and order of magnitude to near-zero levels (a direct quote from the study).

Several years ago, I flogged my Dmax pulling our RV through the Rockies and into the desert southwest for summer vacation. I let the sump get as low as I could tolerate on the dipstick. I ran that engine with no mercy in regard to throttle; if I wanted to move, I floored it, at times for minutes on end in uphill pulls out of the valley floors and over ranges. I am sure the turbo temps got hot; the EGT was maxed at OEM limits around 1300F countless times on the trip. And when I got back, and pulled the UOA, everything was completely normal; totally within specs for both the wear metals and the lube conditions. All on dino 10w-30 Rotella TP.


Is there a reason to fear lube degradation? Sure. But not at 250F.


Great details.

I note as well that no one specifically spoke to the fact that the oil temp varies quite a bit by location within the engine. So sump temp might be 250, but oil in the heads or other hot spots may be quite a bit higher in temp...

 

[dustyroads]

Originally Posted By: SteveSRT8
Originally Posted By: dnewton3
I think we need to clarify the question here, or more specifically, understand that there are actually two questions likely being addressed:
1) what is a safe temp for the ISX
2) what is a safe temp for the lube

I don't know enough about the operational parameters set into the PCM for the ISX; someone else will have to help out here.

As for the lube, 250F is in no way unsafe. Even a conventional lube can provide a good performance if the base stock is of good quality. I believe an ideal temp would be 200-225F; most would agree about that. But a little spike in oil temp is not going to grenade the engine nor the lube. Even long sustained runs are tolerable. If you were to approach 300F in the sump, I would be concerned. But not at 250F.

And just for reference, before any of you go off half-cocked and say I'm nuts, I'll offer this bit of information ...
In the infamous GM filter study (881825), they ran the DD-60 engines at full load, with the sump at 250F for the entire duration of all the tests. Eight hours at a time. Repeated several times. On conventional lube from 1988.

And while we also would agree that massive oxidation insolubles are a bad thing, I'll remind you all that some amount of high-heat oxidation is actually a good thing, because it promotes the TCB (tribo chemical boundary layer) formation on the part wear surfaces. Or have you all forgot about SAE 2007-01-4133? This anti-wear layer of oxidation byproduct is actually a good thing, and is bolstered by higher heat. Once it is established, wear rates typically drop precipitously by and order of magnitude to near-zero levels (a direct quote from the study).

Several years ago, I flogged my Dmax pulling our RV through the Rockies and into the desert southwest for summer vacation. I let the sump get as low as I could tolerate on the dipstick. I ran that engine with no mercy in regard to throttle; if I wanted to move, I floored it, at times for minutes on end in uphill pulls out of the valley floors and over ranges. I am sure the turbo temps got hot; the EGT was maxed at OEM limits around 1300F countless times on the trip. And when I got back, and pulled the UOA, everything was completely normal; totally within specs for both the wear metals and the lube conditions. All on dino 10w-30 Rotella TP.


Is there a reason to fear lube degradation? Sure. But not at 250F.


Great details.

I note as well that no one specifically spoke to the fact that the oil temp varies quite a bit by location within the engine. So sump temp might be 250, but oil in the heads or other hot spots may be quite a bit higher in temp...


I can only speak to my Volvo, but my oil temps that I posted earlier are measured in the sump. I don't know what it gets to within the engine, except to say it gets a bit toasty.

So if my sump temps remain at 245 all the time, does that mean the oil is being pushed to the limit in the turbo and cylinders? It would seem so to me. I'm anxious to see what the oxidation shows when I get an analysis done. Just curious because I've never had a truck engine allowed to run so high all the time.

 

[dnewton3]

The sump temps are typical for the industry.

Certainly oil gets a bit hotter in the "hot spots", but we need to be VERY careful to understand the topic of thermal energy transfer and not just focus on a "temperature" of some local spot.

Thermal energy transfer takes many things into account, and focuses more on the ability of the medium to carry about heat energy. Often expressed in BTUs or Joules, the energy is quantified as a matter of being able to reconcile an exchange rate. Temps at some measurement point are only one part of the equation; others being volumetric flow of the medium, rejection point capacity, etc.


I've used this analogy before, but it helps some folks understand ...

Consider lighting a candle at home and place it on the counter.
Now, what happens if you run your fingers over the tip of the flame?
- if you quickly pass your hand over, very little heat is sensed
- if you slowly pass your hand over, moderate heat is sensed
- if you hold your hand statically over the flame, extreme heat is sensed
This all has to do with the amount of duration of exposure, the mass of your hand, the input of flame energy, etc.

In my example, the variable is the time; the slower the "flow" of my hand over the flame tip, the more exaggerated the effect on my flesh. But the flame energy never changes; the tip stays the same temp (hot!). So if we had a large group of people helping me with the experiment, conceptually we could all form a "circle" where our hands would move over the flame, then out of the flame long enough to reject the heat (via air and blood circulation) away from the skin surface. If enough hands were present, we could soak up all the heat at the tip, and moving fast enough would not ever damage our fingers.

When oil flows over a "hot spot", it does NOT get to the same temp as that hot-spot, if the lube system is well designed. For every molecule of oil that rides right up against the heated surface, there is one right behind it ready to take away some heat as well. It's a "chain of events" where the cooling medium (oil) is constantly being cycled between portions of the engine that either induce (hot areas) or reject (coolers) heat energy. Whereas the EGTs in an engine might get up to 1300F, the oil never gets anywhere near that hot; it's not in direct contact with the EGs. The lube isn't given enough time to fully accept ALL energy; it only has to take a small portion away, for every unit of measure you imply (gallons/hour; liters/min; etc). The WHOLE of system capacity (when properly designed) can accept the entire load of energy necessary for safe operation of the equipment, but the lube will never get beyond it's reasonable limit.

If your oil is getting cooked to a point of damage, it's not the fault of the lube; it's a design flaw. In a well-designed lube system, the oil will be kept at reasonably safe temps, regardless of what "hot spots" might be present.


Therefore, it's common for oil temps to be measured at the sump, because that's where the "balanced" temp exists. Oil will always be a bit warmer in the engine and a bit less at the cooler, so they take the average in the sump (typically).

Do not confuse a safe sump temp with the concept of thermal exchange rates. A very hot surface (head or turbo housing) may get 500F or more, but the oil will not rise to that temp if the volumetric flows pulls enough heat away with each individual unit of measure.

 

[dustyroads]

Thanks dnewton for a good analogy. Even my simple mind can comprehend it when you put it that way.

I still have concerns about running the higher temps long term just because it's new to me. It used to be that 245F was a temporary thing, during a long grueling pull.

I'll feel better once I see some UOA's (assuming they're ok).

 

[SteveSRT8]

I will always have a hard time believing that when my engine is running at full power output and oil is directed precisely at the bottom sides of the piston crown that the oil does not become a bit hotter than my sump indication.

I understand the duration angle, certainly seems obvious. And I have been told by Mobil One in an email that 300 degrees was aok with them as far as degradation goes.

But some oil in some engines in some usage may exceed sump temps by some amount if temps are already high...

 

[Doug Hillary]

Hi,
SteveSRT8 - You are of course correct. The lubricant is subjected to various pressures and temperatures as it flows within an engine

This one reason why ACEA has always included a HTHS viscosity component (at 150Cc - 303F) in its Regimes - and ACEA is a collective of Vehicle/engine manufacturers!

The "static" temperature of the lubricant in the sump is an important one as it really is the "start out point" for the engines lubricant flow! The maximum allowed here by an OEM has been derived at after much Testing - Lab, Prototype and in Field. IME lubricant suppliers to the OEM are heavily involved at each stage

An IR Temp testing will give you some idea of this - if only an indication!

 

[Garak]

Originally Posted By: Doug Hillary
The "static" temperature of the lubricant in the sump is an important one as it really is the "start out point" for the engines lubricant flow! The maximum allowed here by an OEM has been derived at after much Testing - Lab, Prototype and in Field. IME lubricant suppliers to the OEM are heavily involved at each stage

Thanks, Doug. That's worth repeating, if you ask me. With proper gauges, we may know what the sump temperature is, but only those involved in the real testing know what's happening in the rest of the engine, given that "starting point." Therefore, it's well worth paying attention to whatever limits they set on sump temperatures.

 

[A_Harman]

Originally Posted By: SteveSRT8
I will always have a hard time believing that when my engine is running at full power output and oil is directed precisely at the bottom sides of the piston crown that the oil does not become a bit hotter than my sump indication.

I understand the duration angle, certainly seems obvious. And I have been told by Mobil One in an email that 300 degrees was aok with them as far as degradation goes.

But some oil in some engines in some usage may exceed sump temps by some amount if temps are already high...


Yes, the oil that has been sprayed on your piston undercrowns will be hotter than the oil that hasn't, but that is sort of an impossible measurement to get because it mixes with all the other oil that's flying around the crankcase. It's a very trial and error thing tuning piston cooling nozzles. Mostly the development engineer does piston metal temperature measurements in short term max power tests while varying nozzle dimensions. He stops when he gets safe temperatures for the alloy being used, or when he gets the minimum metal temperature for the minimum oil flow.

Some areas of an engine are more prone to the dead end effect, where oil goes in and can't get back to the sump. Oil that gets past the scraper ring on a piston is subject to top ring reversal temperatures and will eventually get into the combustion chamber and burned. This is where an oil will bake at temperature over ~450F, leave deposits, and possibly cause sticking in the groove.

Yet another stresser of oils is the hot shutdown. This is especially bad on turbocharged gasoline engines that don't have water-cooled bearing housings. If an engine is shut down immediately after running for a few minutes at high power output, the latent heat contained in the massive engine housings will travel into lower temperature zones. In a turbocharger, this means that 1650F+ temperatures that exist in the turbine housing will transfer to the bearing housing and cook the floating shaft bushings and any oil that is left in the clearance. Do this enough times, and the oil will leave carbon deposits that can damage the shaft bushings.

 

[fpracha]

Originally Posted By: A_Harman
Originally Posted By: SteveSRT8
I will always have a hard time believing that when my engine is running at full power output and oil is directed precisely at the bottom sides of the piston crown that the oil does not become a bit hotter than my sump indication.

Mostly the development engineer does piston metal temperature measurements in short term max power tests while varying nozzle dimensions. He stops when he gets safe temperatures for the alloy being used, or when he gets the minimum metal temperature for the minimum oil flow.

Some areas of an engine are more prone to the dead end effect, where oil goes in and can't get back to the sump.

Yet another stresser of oils is the hot shutdown.

+1.
All these explanations are great to understand the stresses on the oil and engine parts where maximum temperatures occur coupled with minimum oil flow and volume condition.

The real dilemma in preventing all this "engine and oil damage" is whether to use thinnest oil grade for its maximum flow capabilities (a 16 or 20 or 30 or 40 grade is to be used ??? ) combined with higher dose of special additives like liquid moly and boron , or simply use the heaviest oil allowed by the engine's design engineers ?

 

[Garak]

I would say, at least specifically for a diesel or heavy duty applications (such as my experience in agriculture), follow what the OEM recommends and watch temperatures. For the most part, the OEM lists warning temperatures and critical temperatures for a very good reason. Equipment operated as intended while properly maintained usually doesn't fall afoul of those limits. As Doug already mentioned, when working in dusty environments, such as agricultural ones, one has to pay attention to ensure that fans are able to move the air as needed and things are free and clear. Where an overheat situations happens there, it's usually because of misuse of equipment or something in the cooling system being clogged or blocked or damaged.

 

[Doug Hillary]

Hi,
fpracha - IME you are best to use the lubricant specified for the application and climate environment by the OEM

You should avoid the use of any supplementary additives!!

 

[Shannow]

Originally Posted By: fpracha
The real dilemma in preventing all this "engine and oil damage" is whether to use thinnest oil grade for its maximum flow capabilities (a 16 or 20 or 30 or 40 grade is to be used ??? ) combined with higher dose of special additives like liquid moly and boron , or simply use the heaviest oil allowed by the engine's design engineers ?


Flow isn't lubrication, and with a positive displacement pump, there isn't any real difference.

I DO get where you are at, and your point.

Check out the article that I linked to a little while ago, as it possibly answers some of your questions.

 

[Shannow]

oops, here's the link.
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3741762/HD_engine,_economy_and_wear_5W#Post3741762

 

[HerrStig]

Originally Posted By: chrisri
According to older truckers Deutz air-cooled engines would actually seized in hot weather due to,overheating /metal expansion. Oil would be boiling inside oil pan. After cooling down they would just start truck and drive away. Maybe it's bull, but few truckers told me similar anecdotes.
"Howley and Davidson" motorbikes did the same thing.

 

[HerrStig]

Originally Posted By: SteveSRT8
Originally Posted By: dnewton3
I think we need to clarify the question here, or more specifically, understand that there are actually two questions likely being addressed:
1) what is a safe temp for the ISX
2) what is a safe temp for the lube

I don't know enough about the operational parameters set into the PCM for the ISX; someone else will have to help out here.

As for the lube, 250F is in no way unsafe. Even a conventional lube can provide a good performance if the base stock is of good quality. I believe an ideal temp would be 200-225F; most would agree about that. But a little spike in oil temp is not going to grenade the engine nor the lube. Even long sustained runs are tolerable. If you were to approach 300F in the sump, I would be concerned. But not at 250F.

And just for reference, before any of you go off half-cocked and say I'm nuts, I'll offer this bit of information ...
In the infamous GM filter study (881825), they ran the DD-60 engines at full load, with the sump at 250F for the entire duration of all the tests. Eight hours at a time. Repeated several times. On conventional lube from 1988.

And while we also would agree that massive oxidation insolubles are a bad thing, I'll remind you all that some amount of high-heat oxidation is actually a good thing, because it promotes the TCB (tribo chemical boundary layer) formation on the part wear surfaces. Or have you all forgot about SAE 2007-01-4133? This anti-wear layer of oxidation byproduct is actually a good thing, and is bolstered by higher heat. Once it is established, wear rates typically drop precipitously by and order of magnitude to near-zero levels (a direct quote from the study).

Several years ago, I flogged my Dmax pulling our RV through the Rockies and into the desert southwest for summer vacation. I let the sump get as low as I could tolerate on the dipstick. I ran that engine with no mercy in regard to throttle; if I wanted to move, I floored it, at times for minutes on end in uphill pulls out of the valley floors and over ranges. I am sure the turbo temps got hot; the EGT was maxed at OEM limits around 1300F countless times on the trip. And when I got back, and pulled the UOA, everything was completely normal; totally within specs for both the wear metals and the lube conditions. All on dino 10w-30 Rotella TP.


Is there a reason to fear lube degradation? Sure. But not at 250F.


Great details.

I note as well that no one specifically spoke to the fact that the oil temp varies quite a bit by location within the engine. So sump temp might be 250, but oil in the heads or other hot spots may be quite a bit higher in temp...
You used a good quality oil in the RV.

 

[SteveSRT8]

Originally Posted By: Doug Hillary
Hi,
SteveSRT8 - You are of course correct. The lubricant is subjected to various pressures and temperatures as it flows within an engine

This one reason why ACEA has always included a HTHS viscosity component (at 150Cc - 303F) in its Regimes - and ACEA is a collective of Vehicle/engine manufacturers!

The "static" temperature of the lubricant in the sump is an important one as it really is the "start out point" for the engines lubricant flow! The maximum allowed here by an OEM has been derived at after much Testing - Lab, Prototype and in Field. IME lubricant suppliers to the OEM are heavily involved at each stage

An IR Temp testing will give you some idea of this - if only an indication!


Thank you for that clarification, it is indeed good to know that the sump temps are carefully calculated to allow for the uneven heating...

 

[SteveSRT8]

Originally Posted By: A_Harman
Originally Posted By: SteveSRT8
I will always have a hard time believing that when my engine is running at full power output and oil is directed precisely at the bottom sides of the piston crown that the oil does not become a bit hotter than my sump indication.

I understand the duration angle, certainly seems obvious. And I have been told by Mobil One in an email that 300 degrees was aok with them as far as degradation goes.

But some oil in some engines in some usage may exceed sump temps by some amount if temps are already high...


Yes, the oil that has been sprayed on your piston undercrowns will be hotter than the oil that hasn't, but that is sort of an impossible measurement to get because it mixes with all the other oil that's flying around the crankcase. It's a very trial and error thing tuning piston cooling nozzles. Mostly the development engineer does piston metal temperature measurements in short term max power tests while varying nozzle dimensions. He stops when he gets safe temperatures for the alloy being used, or when he gets the minimum metal temperature for the minimum oil flow.

Some areas of an engine are more prone to the dead end effect, where oil goes in and can't get back to the sump. Oil that gets past the scraper ring on a piston is subject to top ring reversal temperatures and will eventually get into the combustion chamber and burned. This is where an oil will bake at temperature over ~450F, leave deposits, and possibly cause sticking in the groove.

Yet another stresser of oils is the hot shutdown. This is especially bad on turbocharged gasoline engines that don't have water-cooled bearing housings. If an engine is shut down immediately after running for a few minutes at high power output, the latent heat contained in the massive engine housings will travel into lower temperature zones. In a turbocharger, this means that 1650F+ temperatures that exist in the turbine housing will transfer to the bearing housing and cook the floating shaft bushings and any oil that is left in the clearance. Do this enough times, and the oil will leave carbon deposits that can damage the shaft bushings.


Thank you for this detailed info. This is why we love this place! Having guys with real experience within the industry is an amazing asset...

 

[Pontual]

Air cooled engines need special attention to engine baffles and ducts. Some mechanics disturb the rigging of them. They direct the air flow and specially hold pressure over the engine fins and oil cooler. That is what take the heat out of the cylinder/head assembly.

 

[TiredTrucker]

Originally Posted By: A_Harman

Yet another stresser of oils is the hot shutdown. This is especially bad on turbocharged gasoline engines that don't have water-cooled bearing housings. If an engine is shut down immediately after running for a few minutes at high power output, the latent heat contained in the massive engine housings will travel into lower temperature zones. In a turbocharger, this means that 1650F+ temperatures that exist in the turbine housing will transfer to the bearing housing and cook the floating shaft bushings and any oil that is left in the clearance. Do this enough times, and the oil will leave carbon deposits that can damage the shaft bushings.


I am not sure, outside of racing or a dyno, who runs at full power, under full loading, and then just turns the motor off. Even when pulling hard on a hot day and all the temps up, by the time I coast on down an off ramp, turn down the street and go even a short distance to where I am going to park, temps of oil, turbo, EGT's, coolant have all dropped considerably, so the risk of a hot shutdown are remote. Gas or diesel. And I even use turbo blankets on all my turbos. Only thing I have ever lost on a turbo is an actuator on a VG turbo once. I have never lost a turbo. Two of the last three engines I have had did not have water cooled turbos. My present engine has a Borg Warner 171702 turbo that is not water cooled, has a PTP turbo blanket on it since I bought the truck new, and now has 476,000 miles on it. The first of these last three trucks did 1.4 million miles on the original Holset turbo, again, not water cooled. I do not spend time idling and waiting for some cool down of the turbo. I have an EGT gauge with a sensor place immediately at the outlet of the turbo. Even after a major workout, by the time I get pulled off the highway, drive to where I am parking, the EGT gauge has temps coming out of the turbo at around 400F at most, and usually less. The turbo has cooled dramatically in just a couple of minutes of low power drive time to park. A high volume of air has gone thru there in that time to cool the turbo considerably. Now I suppose that if one is at high power, races into a rest area full bore, slams on the brakes and come to a screeching stop, and immediately shuts the motor off, there might be a problem.

 

[Garak]

That could happen under agricultural conditions, but my dad warned me about that as soon as I started using the equipment. But, there, at least it's feasible to be running at full load and then immediately shutting off.