Rear Axle - Owner's guide says lubed for life

[Doug Kuhlman]

2004 XLT 4x4 with 5.4L
Question: Should I be changing the fluid in the rear diff of my expedition? I've never done it and I've got 230K on the clock. Should I follow the manual that says its good for a lifetime?

Thanks,
Doug

 

[deweysmith]

Unless you submerge it in water or it leaks you don’t need to mess with it IMO.

 

[1997SCEBFEX]

Yes or no is for you to decide.

it's an inexpensive and short amount of time to complete imho. I did mine at year 15. 3 qts and the friction modifier (if you have the LS).

 

[Plati]

If it aint broke, dont fix it? My (excellent) local shop advised change my rear differential fluid at 12 years 160K (2003 XLT 5.4), so we did that. There is a TSB out on that and it advises a change to fluid used. -->http://www.strutmasters.com/v/vspfiles/SMPages/PDFTSB/LincolnNav97-02PDF/TSB05-23-3.pdf

 

[Flexpedition]

Be warned, the friction modifier smells horrible and the scent lingers for hours. Best to do this outside, especially if your garage is attached to your house.

 

[The Ark]

Old post but I changed mine at 12 years and 122k miles on my '12 Expy. Was pretty clean but had just bought the vehicle and wanted to make sure it didn't take any water from previous owner.

 

[ccssid]

My 2021 at 17k miles had s silvery slurry look. The only reason I changed was I was suspect that rear diff may have been submerged in water

 

[armyveterantn]

I have 166k miles on my 2017 and I'm the third owner. I don't know the service history, so I'm probably drain and refill after the first of the year. Gonna go with.... https://www.amsoil.com/p/amsoil-severe-gear-75w-85-100-synthetic-gear-lube-svl/