Isx 15 Oil overheating

[Ozzie18]

I have a 2014 kenworth T660 with 580xxx miles Isx 15 Cm2350 which I've been having issues with high oil temperatures. I understand these engines are supposed to run hotter temperatures up to 245 may within normal range. My truck has the same symptoms that I've read about on this site. If i don't turn on the fan on long pulls the temperature can get up to 265, 270, maybe even 275. Engine service advised light turns on at about 265-270 F. It only does this when loaded and even on a flat road with high winds it has heated up on me. Ive flushed out the coolant, swapped the water temperature sensor, coolant thermostat, they replaced the oil cooler, and just last week they replaced the Oil thermostat and on my very first load going not even 15 miles it got up to 248-250 real quick. Im running out of denver so it still not very hot out this time of year. Thanks for your help in advance!!