Found a few threads that seem to match my symptoms.
I installed a new oil cooler 2.5yrs ago.
I have been running Rotella EC1 for about 1.5yrs.
Flushed with Restore before the switch.
I think my one year of MC Gold is catching up to me.
I change my coolant filter every other oil change as well.
Normal Range for a 6.0's deltas
Around town, I cant really get my temps above 190*, EOT or ECT.
On the highway (did a 120 mile round trip yesterday), unloaded besides some tools in the bed, 60* ambient, my ECT would fluctuate 178-184*.
EOT stayed damn steady at 192-194.
Most of the highway run was pretty flat, a few minor hills, and didnt romp on it at all. Stayed right around 65-70mph the whole trip.
Shortly after the highway run, EOT drops within 5* of the ECT.
Not so sure I have an issue?
I finally got that bucking issue fixed with the intermittently sticky IPR, and now this........