I have a new to me 2017 F150 4x4 5.0 with 33k miles on it and decided to change the diff fluids and oil since I don’t know the history of the vehicle prior to me owning it. I didn’t remove the cover, just vacuumed out the diffs and refilled. Ford recommends 75w85 fluid for the front and rear however I went with Mobil 1 75w90 for the front and Mobil 1 75w140 for the back. Does anyone else use these weights and are they appropriate? I chose 75w140 for the rear because they 2015 models were originally spec’d to 75w140 and assuming the differentials are the same I’d rather prioritize wear protection over MPG. For the front, 75w90 was readily available and I rarely use 4WD. I also used Mobil 1 synthetic 5w30 oil to try to protect the engine better and reduce some of the noise however I am considering going back to 5w20 just for warranty sake. I’d like to keep the truck for 10 years so I’m curious to see what everyone’s preference is with engine oil and diff fluid on 2015-2020 F150s.