I don't know that I would worry that much about it. I saw that and a little more towing that exact amount up the continental divide in WY in late Dec, truck normally runs around 8 or 9 normal driving.
Some guys will tell you it should be the same if you are empty or WOT up a hill with max payload, but I don't buy into that.
More load, grade it going to = more heat, and there are times it just won't get it away fast enough.

Was your cooling fan howling?

 

Your truck was working! Totally normal for oil to get hotter when being worked...

If you have any concerns on the differential temp, do an unloaded 60 - 65 mph run (truck fully up to operating temp) on a nice flat freeway. See how much hotter your oil is then and 10 degrees or less is really nice...

 

 

I have to interject a few things - just can't keep quiet. If the thermostat and your fan are keeping the coolant temp down, AND your oil cooler has enough heat exchange area (a critical design criteria), then your temperature difference may NOT go up dramatically when towing. I agree it will go up, but some people have operating data on their personal truck (and posted it) where the "differential" does not go up hugely when towing heavily. Instead of throwing that data out the window, I choose to believe that we ALL have SOME plugging in our oil coolers and so we see higher "differentials" - some more than others. With a perfectly clean system (and some people may have a coolant system that is close to being completely clean), then they will not see large differentials. Some people have reported still being at or even "well" under the 15 degree differential when towing medium loads. Remember we are mainly talking about the "differentials" and not necessarily about the actual values for oil and coolant temp.

I equate it to head gasket leaks. Some people still believe that you either have a big leak or you are fine. They don't seem to acknowledge that there can be small leaks, and leaks that only occur when cylinder pressures reach a certain point.

All that said, I will admit, most people have some clogging and thus flow and effective heat exchanger surface area is reduced. Because of that most of us see differentials higher than 15 degrees when towing heavy, but I really would not like to see them at or above 20 degrees differential. Remember the first TSB Ford came out with actually WAS a 20 degree differential as being the acceptable limit, but then that was meant to be a high engine load test, ie max throttle/boost.

I personally believe that when Navistar designed enough extra heat exchange area to properly perform when towing (assuming a clean system - they didn't anticipate the bad Gold coolant) - This seems especially evident since they added the extra cooling row plate (flow path and heat exchange area) to the oil cooler after a lot of Ford oil cooler failures had occurred.

Just a final note added - to get the "differentials" closer and closer, it takes exponentially (log mean temperature difference factor) more heat exchange area. So you do most of your cooling (oil temperature drop) in the first part of the exchanger. That is why you have more capacity for working the engine hard without significant penalty (to a point anyway). Not that you can ever get to the same ending oil temp with higher heat loads as with lower ones, but it is why you can get close (again - up to a point). And before the comments come in, I realize that the oil cooler heat exchange area is fixed by design (after Navistar added the extra row for coolant). However the effective or usable area does diminish as you plug up passageways (as does the coolant flow itself). The heat transfer coefficient also drops as you foul the surfaces of the heat exchanger. Lots of incentive to keep the system clean.

 

While people will have somewhat lower deltas (actually differential temperatures, not really "deltas") under normal driving vs when you when towing 5k lbs up a somewhat steep incline, you should be happy w/ how your system is working. It looks quite acceptable! Some people see over 20 or even 30 degree differentials under those same circumstances (which is obviously unacceptable IMO).

 

 

 

 

Don't worry about it. The coolant has the benefit of a huge fan to increase the rate of heat rejection through it's fluid-to-air cooler(aka the radiator). The oil might actually reject LESS heat into the coolant under heavy operation because of the flow rate city of the fluids through the cooler. Or that could be backwards. Not an engineer

Fan might not be audible until 100% engagement, there's a step below in the 60%DC range where it pulls a lot more air than unlocked but still isn't "loud".
https://www.ford-trucks.com/forums/1...l#post17351202

 

 

You could always do the "blue wire mod", so when you get worried about high temps you can flip a switch and about 30 seconds later the fan will lock up full on.
Then you can hear that baby roar...........might think you just lifted off the tarmac.

 

I've chatted with you a few times on a few different platforms. I'm really struggling with a situation. It's been a few months since we last spoke. 2006 ford f350 swd. larriat fx4 6-1/2 factory bed. ... does not have factory bed. Has 9ft flat bed. Overlaod spings and shocks. Welder, tools and tool box. Total gross weight is 13,500lbs l. Edge evolution. Kc stage 2 turbo. New ficm. We last spoke about my eot and ect being significantly different. You suggested to replace the sensors. I did. I'm still having the same issue. However. The oil temp isn't as lazy as it was. But my oil temp never gets over 185. But my coolant temp is on average 25-32 degrees above my oil temp. Now, I've put new oil cooler in. Has about 3000k miles on it. Change coolant filter frequently. Using ELC coolant. Head studs ford gaskets. All recent within the last 8k miles. And have had this issue the entire time.Now when I first fire it up. Oil temp is always warmer than coolant. By a few degrees. Once coolant warms up. They are l9cked together untill oil temp reaches about 170. Then coolant starts go up. And it goes up gradually. On the freeway running 70. My oil temp is 167-180. And my coolant temp sits between 204-208. . 208. Fan kicks on, oil temp drops. Like it should. I live on a grade. On my way home it's gotten hot a few times, depending how hard I'm driving. I've just been playing with it to get data, the grade is about 3 miles long. I have seen as high as 235 coolant temp and 200 oil temp. That's running 70 up the grade. On average with tow hual on. And crusing 45, it runs 212-215 coolant and 175-180 oil temp. Everyone says 15*point spread. But as far I understand that only apply to oil temp being higher than coolant temp. I do believe I have a leak in my heater core. Because I smell coolant when heat is on. And occasionally I have to put about an ounce of coolant in to top off. So it's not substantial. Now going hack to the 15* delta spread. Everyone says unloaded do a freeway run. Should be 15*. That's not an option for me. Bed is welded to frame. Welder is welded to bed. So I guess my question is . Given the weight of the truck. Would that be considered under a constant load? I'm mean it it be like a stick truck dragginga n empty car trailer around. And if it under constant load. Would the deltas be concerning given that the cool8ng system if functioning as it should. And oil temp isn't going over temp. But devils advocates says that if oil temp isn't up to temp then I'm chasing harm. Because oil viscosity hasn't reached optimum parameters. I'm gonna drive it untill blows. But I mean this has been driving me nuts. I'm afraid to to my excavator. I'm afraid to tow anything. . A penny for your thoughts.

This was 5min after returning home

This was 30min after retuning home. Letting idle

 

That’s interesting numbers you have there

whats overnight cold soak temps read at KOEO

 

Sorry, I need reminders ...........

Didn't you say your oil cooler is still an "oil-to coolant" cooler (OEM style), not like the air cooled one from Bullet Proof Diesel?

What scan tool are you using?

Where did you buy the sensors?

Disconnect the EOT sensor and then report what the oil temperature reading does. On every engine I have looked at, it is the coolant temperature that experiences the more rapid increase in the first phases of engine operation. Then the oil temperature reaches, and then exceeds, the coolant temperature before it stabilizes.

My truck gross weight is about 9500 lbs. now, so it is always a bit loaded down, but clearly not quite up to yours. Still, an extra 4000 lbs isn't a crazy increase.

As a reminder - the theory behind the "temperature differential" is just to use as an evaluation of the health of the oil cooler. Obviously you want to control the ultimate oil temperature itself, but the differential across the "plate style" oil cooler can also be an important indication of the mechanical stress that the cooler is seeing (thermally induced). The 6.0L sure did see a LOT of oil cooler failures in the early days. It wasn't always just about gasket quality (but Dorman sure showed us their capabilities when they put out their product, lol).

Also, just curious - What fan clutch are you running?