Well, it seems to be a mystery because the internet claims the PTUs are failing left and right. I've read it more than once the Police Interceptor Sedan/Utility are going through PTUs very frequently even with their PTU coolers. Talking to Ford (not dealerships but people at Ford) this seems to be news to them. The UOAs should tell us whether the oil has thinned/thickened, how much metal wear there is, etc... at least give us an idea whether it is the low fluid capacity, overheating, or something else.
To me, driveline stuff is different, I typically use Red Line synthetics out of habit. A lot of the VOAs/UOAs showed Mobil 1, Royal Purple, and a few other synthetics tend to be on the thin side - and its something that's not changed as often as engine oil so I don't mind paying more. Whereas the UOAs for synthetic engine oils weren't that different from non-synthetic on the same type of engine at the same change intervals due to fuel dilution and thinner viscosity regardless of whether it was the least expensive oil or boutique engine oil.