Has anyone used anything other than the Ford Motorcraft 75W-140 synthetic rear axle lubricant for the rear diff? Results? I am planning on servicing mine very soon. 2016 F-150 3.5 EB.

 

Why would another 70W-140 synthetic work differently? What results would you expect people to report? I filled it with Mobil 1 and it drove fine?

 

I believe your year uses 75w85.

 

Motorcraft 75w85 Synthetic

some people run 75w140 if they tow a lot, but it is not the recommended viscosity.

 

I use motorcraft 75w140 in my 2016. My last tow averaged 6mpg towing 7500lb trailer into a 30mph headwind. I want that 140 weight in there.

 

Hasn't it all changed to 75W-140?

 

I was just concerned that maybe the Motorcraft has some special ingredients designed specifically for the Ford diffs.

 

I called the local dealer and they said 75-140.

 

The answer is right in your owner's manual. These generation trucks use 75w-85, though the 75w-90 at the store is fine. These trucks spec'd 75w-140 for a long time, which is perfectly fine in the back if you're going to tow IMO.

Front axle fluid: Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant XY-75W85-QL WSS-M2C942-A

Rear axle fluid: Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant XY-75W85-QL

 

OP, what did you go with? I'm thinking about changing my rear diff fluid to 75W-140 after reading how it seems that the recommended viscosity was arbitrarily changed to 75W-85 in 2015.