Operating temps Towing

I have what I think is a weird one. Got a Dash Command Scanner to keep an eye on things while driving. While towing this weekend things just got plain weird. Pulling Heavy over 8000 lbs I used the Tow Haul mode and the truck preformed great. 6 Hour drive through moderately hilled 2 lane highway.
My ECT (Coolant temp) got as low as 131. When this low my egr would read 0% over the next 1-5 min my temps would climb back to 160 where my egr would read somewhere around 5-17% Then the ect would slowly drop back to 131 then the egr would close and this cycle continued. Worse of all my oil (eot) stayed consistently around 239-246. The engine ran strong all day. When I dropped the trailer and headed home I turned off my tow haul and the temps were consistently as follows:
ect (194)
eot (210)

also the trans temp never got above 177
Why would my ect be hotter when in tow haul?

Does the tow haul mode keep coolant colder to help cool trans?