I just ordered Amsoil gear oil

[Navi]

I took the truck to the mechanic today and the front differential fluid got replaced with Amsoil 75w140.

Before the change there was a whirr and on my previous truck was a whirr. I thought this
I took the truck to the mechanic today and the front differential fluid got replaced with Amsoil 75w140.

Before the change there was a whirr and on my previous truck was a whirr. I thought this is how its supposed to sound. Now...no more whirr sound! The driveline is completely silent.

The magnetic plug had a nice bit of metallic sludge just like the rear diff.

 

[Donald]

Im not a big fan of expensive premium oils but as a result of a prior vehicle with front differential problems I decided to go a different course. Ultimately it took a month for the dealer to rebuild it and it was a nightmare. When it comes to gear oil usually Im fine when it comes to whats on the Walmart shelf, but this time after going through a horrendous experience Im now willing to go down a different road.

I looked at all the different data on here, on the web and the Amsoil website. I came to the conclusion Amsoil would be a great bet if not the best bet.

The application calls for 75W85 but instead opted for 75W140. If anything goes wrong here its truly not the oil but the machine itself.

The funny part about this all is somehow all the gear oil people know about these matters when it comes to F150 trucks, Expeditions and Navigators. After my experience I have no problem spending a little more to get the best thats out there.

Thank you Pablo!

Why did you use a different weight gear oil?

 

[z71bill]

I change differential gear oil every ~25K using off the shelf products.

I did one high end rear diff on my Tahoe - Redline IIRC - and after 25K it looked just as dirty and the OEM fill.

I am in the change it more often with quality but not premium lubes -

YMMV

 

[z71bill]

Why did you use a different weight gear oil?

Because he knows more than the engineers that designed it!

 

[Impatient]

Because he knows more than the engineers that designed it!

What parameters were the engineers working to achieve? I’m not sure “parameters” (or priorities or properties?) is the correct word, but didn’t Ford change the fluid specs in 2014-2015 (or whenever it changed), and why were they changed? It seems to me the engineers did a reasonably good job getting the diff’s to work reasonably well on ultra-thin gear oil, but did the priorities change? Why? And note my use of the word “reasonable” instead of some superlative.

Wear is one thing, but what about heat (which I suppose relates back to wear). Are there outboard bearings affected by their fluid choices? Do Excursions have solid axles, or independent? Would wear parameters differ in a unit subject to Navi’s use case vs a unit involved in towing, or one getting 95% rural highway use?

But IF 75w-85 is the weight “preferred” by the engineers, but someone decided to go against that spec, wouldn’t it make sense to not go to the far opposite end of the spectrum? 85 -> 90 -> 110 -> 140.