Rear differential fluid change?

The owners manual for my 2014 LTD says the rear diff fluid is synthetic and no need to change the fluid for the lifetime of the vehicle...unless there's an obvious leak or the axle was driven under water. I've got neither of those.

I mentioned this to my mechanic and he said yeah he knows what Ford says, but if it was his truck, he'd change it. It's approaching 62,000 and I'm doing overall fluids changes...but holding off on the rear diff.

Probably can't hurt, but it's another $100 bucks! Thoughts?

Would not even consider changing if it hasn't been under water, till at least 100,000 miles. Even on the the old gear oil they did not recommend changing it.

Owners manual says it's good, but 100k is a lot of miles for a gear oil. Changing the fluid is much cheaper than changing diff parts. "Lifetime"fluid, but changing them more often will likely increase that lifetime.

rollinstone said:

The owners manual for my 2014 LTD says the rear diff fluid is synthetic and no need to change the fluid for the lifetime of the vehicle...unless there's an obvious leak or the axle was driven under water. I've got neither of those.

I mentioned this to my mechanic and he said yeah he knows what Ford says, but if it was his truck, he'd change it. It's approaching 62,000 and I'm doing overall fluids changes...but holding off on the rear diff.

Probably can't hurt, but it's another $100 bucks! Thoughts?

Click to expand...

Where does it say that?
My 2014 owners manual says change every 150000 miles
.. but they call it "rear axle fluid" so is that the diff?
(I'm gonna do all 4 at 110,000)


and WTH is an accessory drive belt(s) ... serpentine?

MrSticker said:

Where does it say that?
My 2014 owners manual says change every 150000 miles
.. but they call it "rear axle fluid" so is that the diff?
(I'm gonna do all 4 at 110,000)
View attachment 40541

and WTH is an accessory drive belt(s) ... serpentine?

Click to expand...

Yes


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62k miles I personally wouldn’t be in a hurry to change it but it depends what kind of life if it’s lead. If you know the history and it’s been babied I wouldn’t do any of those yet. If you’ve been hard on it, change everything. If you don’t know, change everything. Pretty much everybody agrees hat the lifetime or 150k mile stuff is bogus. If you’re changing everything else I would do rear diff right along with it, it works hard.


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Also for that price tag get yourself a little pump and do everything yourself, it’s all just drain and fill.


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Stickler.......yes and yes

The diff has synthetic in it, it's not like the old days and water and leaks are what kills rear ends. (pumpkins, bangos, diffs, rear ends, third members) .......old mechanics know this stuff.

MrSticker said:

Where does it say that?
My 2014 owners manual says change every 150000 miles
.. but they call it "rear axle fluid" so is that the diff?
(I'm gonna do all 4 at 110,000)
View attachment 40541

and WTH is an accessory drive belt(s) ... serpentine?

Click to expand...

Page 500 of my 2014 manual says the same thing. However, on page 340 it says "Your vehicle's rear axle is filled with a synthetic rear axle lubricant and is considered lubricated for life. These lubricants are not to be checked or changed unless a leak is suspected, service is required, or the axle has been submerged in water."

I think I found where I messed up...unless service is required...I missed that. So, service is required on the rear diff at 150,000 miles, which I guess is Ford's definition of "life.". So, when it gets to 150,000 I'll change it. Thanks for motivating me to go back into the manual and take a look.

FWIW, I just had the front diff passenger side axle seal replaced today...pesky seep. We checked the diff fluid and it is a really dark/black and well-used color...not healthy looking at all. Will be changing that out right away. Odd, though...because I have hardly ever driven the truck in 4WD...not even 5-6 miles on snow and once up a steepish muddy track...although it had about 28,000 on it when I bought it...maybe previous owner?? Truck was immaculate when I purchased it.