Differential Fluids

[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