I'm running the DpTuner Infinity tuner. Stock tune. Just using the infinity to monitor parameters.
Noticing my EOT through the tuner is reading 225ish empty, on a 6-7% grade,, 70 degrees at about 70mph. 210ish putting around at 40mph.

Last summer I saw as high as 245 towing 13k on the same grade at 90 degrees. I could have gotten it higher but nursed it home. Never boiled over and the gauge on dash has never went over half way point.
Is it normal for EOT to be reading so high through the PCM? But the dash gauge showing normal?

 

In a word, yes...

I run 205° thermostat and have for the past 7 years of towing heavy cross country. I typically see 205 - 225 unloaded depending on ambient air temperature and road conditions. I typically see 205 - 225 loaded (up to 12,000 lbs in tow) depending on ambient air temperature and road conditions. Yes, they are the same measurements.

Below is a snip of a FSL data log where you can see an EOT reading of 217° sustained while towing up a grade last summer in 95° ambient heat towing the 5th wheel. I run Rotella ELC in my truck and have for 7 years. These sort of temperature readings are typical for me, but may not be for others or you.



Recently, another FTE'r wrote...
Conventional oil starts breaking down at 250° and synthetic is rated up to 450° based on my very brief period of research. I don't know what the maximum sustained operating temperature is of conventional oil is, but if you are concerned about your EOT, perhaps look into it if you are running conventional oil. I have never seen an EOT reading this high, but each truck is different and what is normal for one truck may not be for another.

What I am saying is that you should keep track of your readings and establish a baseline. I do not see anywhere near 265° from my EOT reading, but I don't know what sort of coolant he was using, perhaps it was distilled water with nothing mixed in it. Perhaps his thermostat was stuck and would only open when it was higher than the set temperature. Perhaps his fan was not functioning properly and the engine was not receiving the proper cooling. Perhaps his radiator/condenser were plugged or had a lot of bent fins. Perhaps he had a big bumper on the front that did little for cooling. Perhaps he ran the truck hard all the time at 3000 RPM.

I don't know...

Establish a baseline, keep an eye on it and move forward from there.

 

While I was doing some other work to it over the winter I replaced the thermostat with another 203, New fan clutch, New coolant filter and hosed out the core/fins.
I flushed the cooling system, installed the coolant filter and start running ELC about 10 years ago
at just under 100,000 miles. 145k on it now..
Ive also been running T6 since 04.
I did notice my ac condenser is pretty hammered from hail so that could be restricting some air flow..

 

Looks like you are doing almost everything you can to keep it running strong. Some people only achieve 10 MPG where others get close to 20 MPG. Each of these trucks are different.

Perhaps the observed temperature is the happy place for your truck.

Some radiator combs might surprise you with the amount of debris you remove. I pulled out a lot if tiny rocks and straightened quite a few bent fins.

Link:

 

What I’ve noticed over the years using an Edge engine monitor and just cruising down the road at speed limits (75ish) with engine up to good temps is take your ambient temp from OH console X 2 + 50 or 60, I.e. 80x2=160 + 50=210 EOT.
EOT = AT x 2 + 50 or 60.

 

Once my engine gets up to normal operating temp, I never see the gauge move AT ALL, even pulling a heavy load up a mountain. On OBS trucks I can always see the gauge move a bit depending on how hard the engine is working. I'm suspicious that the gauge in 1999-up trucks is nothing but a glorified idiot light that won't tell you anything until the engine is already overheated. That's a good reason to monitor EOT. My EOT ranges from about 90 to 104 C (194-219 F).

 

Yep, our temp gauge is just an idiot gauge and once it reaches that magic mark it doesn’t move UNLESS you are truly having a temp problem, then the gauge will move up quickly and you better respond.

 

@Sous pretty much spelled it out for you but I will tell you what my truck does..

Once warmed up around town it hangs out near 200 EOT poking between lights if not sitting to long it may drop to about 185-190 if sitting.

On open road around 70 mph it hangs out near 205-210 EOT and sometimes 215 EOT if rolling hills are involved.

Also something to think about and I am bad as my drive to the airport where I do most of my training is only 5 minutes away, if your oil does not get warmed up and stay there long enough you will not burn the moisture out.

 

Have you verified the oil is actually reaching those temperatures? With the sensor being in the hpo reservoir makes it pretty easy to shoot it with an infrared thermometer in a couple spots on the reservoir. If it's within a few degrees then you know it's good.

 

Old Smokey is back on jack stands.
Again.
Ill get it back on the road this week and will hook my little trailer up and do some testing. Check the HPOP with my infrared.