I have a 2014, just went through the hassle of dealing with the oil cooler crack around 39K. I also have the issue with heating and the video that popped up on youtube ... bingo - have my attention. I have yet to take it in for the inadequate heating.
Forgive my layman's take, appears improper cleaning of the motor during mfg - leaving debris which causes sludge to impact the radiator/heater/cooling system.
Forums helped me lock down a dealer on the oil cooler crack ... what is everyone seeing in their jeeps?