Chaning Differental oil ???

ilvtravln wrote:
Have an 03 F350, 90K miles, how often should the diff. oil be changed ? Ford lists the oil that came with is as synthetic. We do about 1/3 towing and the rest around town. Thanks

My 2wd '03 2500 Dodge/Cummins has 377k+ miles now on the 11.5" AAM rear axle.
I bought the truck new and after draining OEM rear axle fluid has nothing but 75w-140 Redline synthetic changed every 50k-60k miles or so.

Depending on truck use the life of the rear axle assy depends on dumping old contaminated fluids and going with fresh fluids.
Makes a difference.

ilvtravln wrote:

Grit dog wrote:
How often? Now. If it’s 20 year old oil. That said once I do an early diff change on a new or new to me vehicle, I go at least 50k between changes with good synthetic gear lube.

PS, if it’s an early 03 7.3 you have a very desirable vehicle if it’s been kept up and basically used only rarely.

Its a 7.3, well kept.

Worth mentioning in the event you’re unaware, depending on the model and options, you likely have a very valuable truck, especially being the newest/last 7.3s made.

Point is it’s worth it to take care of that truck, moreso than most. And they needa little extra care in the fluids department. 7.3 HPOPs are very happy with fresh oil and not happy with extended OCIs.

1320Fastback wrote:
As a person who just dropped $2,440 on a rear end rebuild I'd do it now. My oil was last changed by myself around 5 years ago and now wish I'd done it more regularly. Oil is cheap comparably.

Well, if it was the oil, it would be about the first time I've heard of not-that-old-oil causing a differential failure. More likely not the oil that caused the failure.

wnjj wrote:

1320Fastback wrote:
As a person who just dropped $2,440 on a rear end rebuild I'd do it now. My oil was last changed by myself around 5 years ago and now wish I'd done it more regularly. Oil is cheap comparably.

While that's true, it's also no guarantee that your rear end wouldn't have failed even with fresher oil.

Can't see the differential, so can't say for sure. But what I can say is that in my trucks, changing the diff oil at recommended time made temps run lower. (Transmission made more change).

1320Fastback wrote:
As a person who just dropped $2,440 on a rear end rebuild I'd do it now. My oil was last changed by myself around 5 years ago and now wish I'd done it more regularly. Oil is cheap comparably.

While that's true, it's also no guarantee that your rear end wouldn't have failed even with fresher oil.

As a person who just dropped $2,440 on a rear end rebuild I'd do it now. My oil was last changed by myself around 5 years ago and now wish I'd done it more regularly. Oil is cheap comparably.

2007 F-150 sig pic had about 170K miles, daily driver and towing. I changed it because the diff cover was showing signs of rusting through. Fluid was dirty of course, but no obvious shiny chunks. Gears looked like brand new.

Grit dog wrote:

larry barnhart wrote:
Our 05 chev dually with 116000 miles has had the rear diff changed 13 times. so easy to do I decided to overkill as I do on every fluid for this truck. chevman retired from Rving

Lol, I’d love to have the $1000 worth of used oil outta that truck.

Probably closer to $700.00. no labor spent a lot more on the overkill fluid changes but with 116K mores it does run awesome. Looks great sitting in our garage. chevman retired from rving. "Don't frown because it is over but smile because it happened"

I have a '12 Super Duty with the same rear end with ~260k miles. The rear diff fluid has been changed once to date and is dry as a bone so no leaks. Probably need to do it again.

In your case probably every 100k miles is good if there's no leaks.