Change Interval: Rear Diff Fluid

DFW64 · Jul 6, 2011

Is it 50,000 miles?

pog · Jul 6, 2011

i doubt you need to service the diff unless its been submerged in water.

DFW64 · Jul 6, 2011

Entered my VIN and looked it up on Ford.com.

Extreme conditions: 50,000 miles

Normal operation: 100,000 miles

pog · Jul 6, 2011

hmm thought the manual said that ford uses a synthetic oil which didnt need to be serviced unless water got into it. i did mine @ 95k. only reason i did it then was because i had too much fun at the river. i dont see how bad it could get at 50k.

DFW64 · Jul 6, 2011

Don't know...I guess extreme conditions.

I'm at 97,000 and was going to change cause its Texas and I've logged alot of miles in the summer time.

pog · Jul 6, 2011

yeah if your at 97k you could do it. rtv glue the black kind and dont forget friction modifier for the LS

CSIPSD · Jul 6, 2011

pog said:
hmm thought the manual said that ford uses a synthetic oil which didnt need to be serviced unless water got into it. i did mine @ 95k. only reason i did it then was because i had too much fun at the river. i dont see how bad it could get at 50k.

Hook up to a load and watch how hot that sucker gets...

I change mine about every 30-40k

pog · Jul 6, 2011

if i towed i would lol

White_monster · Jul 6, 2011

Change the oil guys. The oil breaks down during use and from heat and loses it's lubrication properties. Also the extreme pressure in the diff will affect the oil.

Pog if you think not changing the diff oil is right then don't change your engine oil cause it's synthetic. I'm not sure where you got this info but your source is way wrong. Diff oil breaks down just like engine oil just it takes longer.

jdgleason · Jul 6, 2011

For what it will cost you to do it.... for the reliability... i would go ahead and do it.

pog · Jul 7, 2011

Dzchey21 · Jul 7, 2011

oil is fairly cheap compared to the bearings and other components in the differential so i would say 50k, mine has been changed 3 times and i only have 40k on the truck LOL, breaking stuff will do that for you.

When i first saw that they were supposed to go 100k i thought they were crazy, its not so much the oil breaking down that i would be worried about it would be the particals in the oil that cause wear, there is no filter to get rid of it and the magnet only catches iron.

cfdeng7 · Jul 7, 2011

:whs: preventive maitnence is a whole lot cheaper than the repairs and leaving you stranded on top of it.

pog · Jul 7, 2011

I was just goin off of what i read. And yes racing and what not all go into count how often stuff should be done. But assuming the truck isnt raced or abused beyond its stock application im sure an avrg joe would be fine not worrying about it before 100k. Ive just never heard of any diff issues on the 6.4 that was caused from oil not being changed. I am all for preventive maitnence