I see quite a few post about high engine oil temp issues, also all of the after market oil coolers are no longer available.
I see no real answer why the engine oil is over heating. I just purchased a travel trailer (6700 lbs.) to tow with my 2015 Ram 1500 with 23,000 miles on it.
The truck has had the re-called oil cooler replaced along with all the other recalls.
Now I'm concerned that this truck will self destruct with these high temps (OIL 272) (COOLENT 248) (TRANS 240) this was on a 6% grade doing 45 mph for about 6 miles.
I had these issues with heat as well, with OEM tune and configuration, pulling 6,000 lbs flat ground with headwind. Added the now no longer sold oil cooler and remote oil filter and lowered antifreeze temp to 210/212 but oil stayed in the 270 range, trans still 220 and above for short periods while pulling in Montana and Wyoming.
At issue is the three way liquid coolant valve on the side of the transmission. It mixes motor oil, transmission fluid, engine coolant in a liquid to liquid heat exchange system, small system, to decrease warm up times. The faster the engine warms up the sooner it gets to EPA exhaust levels. The problem is this system is not an effective cooler, as it is a temperature sharing system. The OEM oil cooler is the same way it is a small liquid to liquid heat exchanger, better for warming than cooling, too small to cool and on the side of the engine out of air paths.
When I installed my external oil cooler I removed the second oil temp load on the antifreeze which netted me a lower water temp. But no positive effect on engine oil or trans fluid temp. The answer is to change the management of the three way valve. When I installed my original GDE tune not only did I gain more HP I also benefited from a different management profile of the three way valve, netting me coolant temps in 220 range, trans fluid 199/200, oil temp 256/265 while towing. I am now running the EPA Compliant GDE tune which again manages the three way valve, with trans tune and I am still experiencing more reasonable temps as well as better transmission shifting.
Most of the tunes on the market change the three way valve management profile, I believe but you should investigate, so they should positively affect your excessive temperature experience. Choose the one you like the best. I have experience with GDE and love it, others have experience with SofaTuneKing and HDdiesel, from what I have read they all perform well so you would probably not loose on any choice.
Our present RV is 6,900 lbs dry. My 2014 is now running on 132,000 miles with 3.92 posi rear end. I do all my own maintenance except for dealer recalls and I am lucky to have a dealer with good eco techs. The only mods I have are the GDE EPA Compliant tune w/trans tune, the external oil cooler w/oil filter and OEM style K&N air filter.
Good luck.