Last weekend I did only power transfer unit. You can not fill any difference with driving or noise, but I know it for sure it extends life of this unit. Those very fine sand metal particles on the magnetic drain plug, and bottom in oil, definitely should be cleaned out. Stink this oil was the worst I've ever feel.
For PTU my Ford Dealer recommend 1.06 lt Motorcraft SAE 75W-140. Genuine bottle cost ÂŁ67 !
So I decided to use different brand. I bought (1 bottle 75W140 GL-5 Red Line) like "escapeforum" users. UK ebay stock auction: 283555719499 with Sealey AK54 Syringe.
I will order as well oils for rear differential and my 6 gears manual gearbox MMT6.
Ford recommend:
.....REAR DIFF...... 1.36 lt Motorcraft SAE 80W-90 (Premium Rear Axle Lubricant)
.....GEARBOX....... 1.75 lt Ford 75W FE (WSS-M2C200-D2)
Red Line alternatives:
2 litres Red Line MT-LV GL-4 (gearbox)
2 litres Red Line 75W-90 GL-5 (rear diff)
All oils are refilled until they comming out. Rear differential haven't got drain plug (oil have to be sucked out and filled by the same plug).
PTU oil change:
https://youtu.be/G8zMXcKk5Es
Escape forum:
https://www.fordescape.org/threads/ptu-and-rear-diff-oil-change.109340/page-3