My wife bought a new 2017 Explorer in Feb 2017. Afterwards I started reading and seeing videos of the PTU and it's abuse of the gear oil. This appears to be because the PTU only holds ~13-18 oz of 75W-140 gear oil and is surrounded by major heat sources, especially in the 3.5 EB. Of course Ford says it's a "lifetime fluid" and not to change it
. Plus it's a real challenge to change it in the 3.5 V-6, no drain plug. Luckily our Explorer is the 2.3 EB and the PTU holds 23.7 oz and has a drain plug. In addition being a 4 cylinder it's subject to less heat exposure. I had the dealer drain and fill it at 9,000 miles and I had it done again at 22,000 miles with Amsoil Severe Gear 75W-140. This was run for 22,435 miles and changed again with the Amsoil. I did an UOA to see how the fluid held up and whether I can run it more miles. I asked Blackstone about going 35,000 miles on the next change of Amsoil. They thought that would be fine. Comments are welcomed.