Differential Fluids

[Boosted]

I'm at the 50K mile mark and looking to change a couple of the other fluids in the truck such as differential gear oil. The manual calls for 75W-85 for the front and rear differentials. I was a bit surprised since the early 2010's F-150's spec'd 75W-140 gear oil for the rear differential fluid.

I'm likely going to deviate off-spec and wondering what others have changed their fluid to.
75W-80 is available in many other brands and is very similar to the OEM grade.

 

[99WhiteC5Coupe]

I'm at the 50K mile mark and looking to change a couple of the other fluids in the truck such as differential gear oil. The manual calls for 75W-85 for the front and rear differentials. I was a bit surprised since the early 2010's F-150's spec'd 75W-140 gear oil for the rear differential fluid.

I'm likely going to deviate off-spec and wondering what others have changed their fluid to.
75W-80 is available in many other brands and is very similar to the OEM grade.

I’m curious - why would you deviate from the Ford specifications for the fluid?

 

[gural]

i have changed in my Exp to orginal
have no issues

 

[HILLY]

I’m curious - why would you deviate from the Ford specifications for the fluid?

More accessible on the market. The 5 points is negligible. They're running thinner for EPA ratings. I went with 75W-90 on my previous Expy when I changed out my drivetrain fluid.

 

[bb37]

If you have the eLSD, does that impact your choice of rear differential lube?

 

[Boosted]

I’m curious - why would you deviate from the Ford specifications for the fluid?

I see how Ford changed the spec to a thinner viscosity for mileage. The Ford spec is not available in many places and Ford is charging more than Amsoil. You can get Mobil 1 Synthetic 75W-90 for ~$9/qt vs. Ford spec is ~$21+ and it takes ~5 quarts.

 

[HILLY]

If you have the eLSD, does that impact your choice of rear differential lube?

No. This eLSD is electronically applied clutches, no friction based. So in this case the spec is not as important, certainly not a 85 vs. 90 difference, and friction modifier is not required either as with an "analog" clutch pack.

 

[BMW2FORD]

This is from Ford,

https://www.fcsdchemicalsandlubricants.com/quickref/axlelubeUS.pdf

 

[HILLY]

This is from Ford,

https://www.fcsdchemicalsandlubricants.com/quickref/axlelubeUS.pdf

Good info.

I went with this last go around, and FM wasn't required as a separate fill. All MY 4th gens were listed on their compatibility chart.

 

[BMW2FORD]

Some fluids do have the friction modifier in it like what you used. Not the Ford fluid. It’s still has to be added to help the clutches.

 

[drscanman]

Good info.

I went with this last go around, and FM wasn't required as a separate fill. All MY 4th gens were listed on their compatibility chart.

View attachment 83905

Thanks for sharing. I have a 2017 with a 3.73 rear axle, how would I know if the rear axle is limited slip?

 

[HILLY]

Thanks for sharing. I have a 2017 with a 3.73 rear axle, how would I know if the rear axle is limited slip?

I would just back over the 3rd gen forum and ask to be sure. Those guys would know more about your truck than we would for the most part.

 

[jpwiseman]

The Owner's Manual for my 2019 Expy seems to contradict itself in regard to the rear diff fluid. Page 512 (Scheduled Maintenance section) says to change the rear axle fluid at 150k miles. Page 391 (Capacities and Specifications) has a footnote for the rear axles that says, basically, the rear axle fluid is a synthetic fluid that is considered lubricated for life and not to check or change the fluid except for leaks or being submerged in water. I'm getting ready to do the 150k miles service myself and not sure what to do on the rear diff. Can anyone clear this up? Thanks.

 

[East-TN]

The Owner's Manual for my 2019 Expy seems to contradict itself in regard to the rear diff fluid. Page 512 (Scheduled Maintenance section) says to change the rear axle fluid at 150k miles. Page 391 (Capacities and Specifications) has a footnote for the rear axles that says, basically, the rear axle fluid is a synthetic fluid that is considered lubricated for life and not to check or change the fluid except for leaks or being submerged in water. I'm getting ready to do the 150k miles service myself and not sure what to do on the rear diff. Can anyone clear this up? Thanks.

No harm in changing the fluid...and actually it'll probably be beneficial.

 

[TheDoug]

The Owner's Manual for my 2019 Expy seems to contradict itself in regard to the rear diff fluid. Page 512 (Scheduled Maintenance section) says to change the rear axle fluid at 150k miles. Page 391 (Capacities and Specifications) has a footnote for the rear axles that says, basically, the rear axle fluid is a synthetic fluid that is considered lubricated for life and not to check or change the fluid except for leaks or being submerged in water. I'm getting ready to do the 150k miles service myself and not sure what to do on the rear diff. Can anyone clear this up? Thanks.

I changed both differentials and transfer case fluids around 50k miles... I was shocked how gross the fluids looked. I personally would not let it go to the 150k mark.

 

[spo0587]

I changed mine without FM, no issues. Just went with full syn 75-90 because it was cheaper. The ford was too expensive like @HILLY said

 

[Boosted]

Does anybody know the following torque specs?

Differential cover bolt torque
Transfer case drain and fill torque

 

[jar0023]

No. This eLSD is electronically applied clutches, no friction based. So in this case the spec is not as important, certainly not a 85 vs. 90 difference, and friction modifier is not required either as with an "analog" clutch pack.

Um…how do you think a clutch pack works if not by friction? The Ford E LSD behaves just like a traditional spring loaded clutch pack LSD until you engage the electric switch that clamps the clutch pack enough to “lock” the clutch pack.

 

[HILLY]

Um…how do you think a clutch pack works if not by friction? The Ford E LSD behaves just like a traditional spring loaded clutch pack LSD until you engage the electric switch that clamps the clutch pack enough to “lock” the clutch pack.

Not sure how that posts reads and comes across from one person to the other, but I can see how I originally wrote that how it can be interpreted. Yes all LSDs for the most part (save Torsen, and I'm sure some others) are working through the act of friction. The Ford eLSD works by actively managing mechanical engagement, plus the added benefit of a locker to clamp them together 100%.

The eLSD uses an electronic control unit (ECU) that monitors wheel speed sensors on the rear axle. When the ECU detects a wheel is losing traction, it electronically adjusts the amount of torque being sent to each wheel via the clutch. The wheel with more traction receives more torque, improving traction and stability.

Most other "analog" LSDs on the market such as the older Jeep Quadra-Drives (WJ) were simply operating by spring loaded clutch packs and the shearing forces of the oil to manage slip.

I also thought I had amended the statement on the friction modifier part as well, and it may have been another discussion, but the FSM does call for it, which most aftermarket oils already have it mixed in. If using Motorcraft oil, it's needs to be added.

 

[montanaday74]

The Owner's Manual for my 2019 Expy seems to contradict itself in regard to the rear diff fluid. Page 512 (Scheduled Maintenance section) says to change the rear axle fluid at 150k miles. Page 391 (Capacities and Specifications) has a footnote for the rear axles that says, basically, the rear axle fluid is a synthetic fluid that is considered lubricated for life and not to check or change the fluid except for leaks or being submerged in water. I'm getting ready to do the 150k miles service myself and not sure what to do on the rear diff. Can anyone clear this up? Thanks.

I'll tell you my experience. 2017 Ford Expedition EL, driven very easy miles, 7-9,000 a year, no off-roading, wood getting, hard driving, just transporting grandkids and groceries. All maintenance work done at our local Ford dealer. At around 70,000 miles our rear differential had to be replaced, which happened just under the expiration of our certified used warranty. A little over a year and a half later, our front differential went. At 82,000 miles our catalytic converter was going out. $2,000 repair. Don't go by the maintenance manual. We learned the hard way.