I have a 2011 STX/XLT F-150 supercrew. Odometer is at about 80,000 km (50,000 mi). I've owned it since about 60,000 km. When I took it to the little shop on the corner for an oil change, they told me that the rear differential fluid is dirty and needs a flush. They said that it should be changed every 50,000 km and probably was never flushed.

Is it true that the rear differential fluid should be flushed every 50,000 km? I have consulted several maintenance schedules (e.g. my printed manual, http://www.ford-trucks.com/how-tos/a...chedule-359521) and I don't see anything about differential fluid.

Maybe it goes by a different name. http://www.lacombeford.com/maintenance.php says, "Replace front axle, rear axle and transfer case lubricant every 250,000 km". Is this the same thing?

I talked to the independent mechanic shop I trust for all my major repairs. They said they only recommend a flush when doing a rear rebuild, but if I want to be sure, I can contact Ford. I'm reluctant to call the dealer because I always feel that they just want to separate me from my money and they'll say yes the work is recommended.

 

Look in scheduled maintenance in the owners manual, it states 150,000 mile
- 240,000 km interval for front and rear differential fluid change

 

I found where my manual says the same but it uses the words "rear axle fluid" rather than "rear differential fluid". I wasn't sure if they mean the same; I guess they do.

The manual also provides more clarity in the Maintenance and Specifications section where it says what kind of fluid to use. The footnote says, the rear axle "is considered lubricated for life. These lubricants do not need to be checked or changed..."

Thanks for helping me find this.