I'm doing a bunch of work on my 2010 Ford Flex Ecoboost. One of the new parts I'm installing is a brand new PTU. The new unit comes from the factory pre-filled with Motorcraft 75w-140 synthetic gear oil. This oil is known to break down and turn to a thick gloppy grease due to overheating when the PTU gear oil is not properly maintained even though Ford claims it's a "lifetime" fill. My old PTU was still functioning at 150k miles, but had quite a bit of output shaft play from wear despite fluid exchanges starting at about 60k miles. I have used the Motorcraft, Mobil 1 and Amsoil SG oils in the PTU and ultimately settled on the Mobil 1 as my top pick. So, I have a few questions for the experts here before I put any miles on this new unit:
1. What fluid should I use for break in and, does it even matter? The Motorcraft has a high dose of moly, but I will not run the Motorcraft gear oil again after the initial fill is drained.
2. How quickly should I do my first fluid exchange after I start driving on the new unit? I am thinking 5K miles might be a good target.
3. What does everyone think about dropping down to a 75w-90? For instance, I've had really good success with Mobil Delvac 75w-90 in other gear applications and it's a really stout product. As an example, my AWD 2016 Sienna uses a 75w-90 in the transfer case and I'm running the Delvac product in it without any issues. I also wonder if Ford spec'd the 75w-140 grade because a) it's the only synthetic gear oil in the Motorcraft lineup and apparently Ford is very proud of this lubricant, and b) originally the PTU was supposed to be sealed for life and they believed that the thicker fluid would not shear down to a low viscosity where damage could occur as quickly. Lastly, I would guess that the lower viscosity fluid would also run a bit cooler in the PTU?
Thanks in advance.
1. What fluid should I use for break in and, does it even matter? The Motorcraft has a high dose of moly, but I will not run the Motorcraft gear oil again after the initial fill is drained.
2. How quickly should I do my first fluid exchange after I start driving on the new unit? I am thinking 5K miles might be a good target.
3. What does everyone think about dropping down to a 75w-90? For instance, I've had really good success with Mobil Delvac 75w-90 in other gear applications and it's a really stout product. As an example, my AWD 2016 Sienna uses a 75w-90 in the transfer case and I'm running the Delvac product in it without any issues. I also wonder if Ford spec'd the 75w-140 grade because a) it's the only synthetic gear oil in the Motorcraft lineup and apparently Ford is very proud of this lubricant, and b) originally the PTU was supposed to be sealed for life and they believed that the thicker fluid would not shear down to a low viscosity where damage could occur as quickly. Lastly, I would guess that the lower viscosity fluid would also run a bit cooler in the PTU?
Thanks in advance.