I just ordered Amsoil gear oil

[Navi]

No issues I guess, just 75W140 is double the viscosity of 75W85. It's going to be overkill especially in the winter. But if the OP tows, I guess it will be better.
https://www.amsoilcontent.com/ams/lit/g2043.pdf (2nd page)

75W85
Kinematic viscosity at 100°C: 13.3 cSt (SAE40 viscosity)
Kinematic viscosity at 40°C: 76.9 cSt

75W140
Kinematic viscosity at 100°C: 25.9 cSt (SAE60 viscosity)
Kinematic viscosity at 40°C: 172.1 cSt

There were very severe issues in the 2022 and 2023 Ford light truck differentials. Differentials were going out under 30000 miles. No one can be sure if these problems have been fixed. Even if they were fixed I feel more comfortable using this thicker gear oil. 75w140 has become popular in the F150 owners community.

Even Redline has zeroed in on this issue stating their 75w140 is popular with F150 owners. However after doing my research I believe Amsoil is the better product here.

Ive learned the hard way that when it comes to Fords light truck line you want to go thicker and it seems thats the case too with GM light trucks as well.

 

[Navi]

I did make a mistake here in ordering the Amsoil. I think @Pablo has some links to order Amsoil so he gets the proper credit. I truly think Amsoil is a great product and I might look more into it in the future. Right now Im on 5W40 Euro oils but willing to consider Amsoils lineup of products.

 

[Pablo]

I did make a mistake here in ordering the Amsoil. I think @Pablo has some links to order Amsoil so he gets the proper credit. I truly think Amsoil is a great product and I might look more into it in the future. Right now Im on 5W40 Euro oils but willing to consider Amsoils lineup of products.

Thanks - if there isn't a product link in a thread, please use the link in my signature.

 

[Pablo]

Amsoil gear oils: https://www.amsoil.com/c/gear-oil/25/?zo=515729

 

[Glenda W.]

Arrived as promised!

 

[The Critic]

Im almost at 15000 miles and thats my thoughts exactly!

What happened with the prior vehicle was I started hearing loud grinding noises at 25000 miles. Took it to the dealer thinking this would take 1 week under warranty and I was wrong. It was 4 weeks and complaints lodged with Ford.

So on this next go round all gear fluids...front diff, rear diff and transfer case getting changed out before 15000. Research done and most think the best long term reliability is with the 75w140 variety. I understand 75w85 is just for the auto makers mandated mpg requirements but not durability.

No amount of boutique lubricants would have prevented this failure. This was clearly a defect, either in the design or in the manufacturing of your unit.

Using this experience to justify the usage of boutique lubricants is misguided at best.

 

[johnmyster]

Strangely I can't find an Amsoil that meets or exceeds GL-5. Only "recommended for." I guess they don't meet or exceed API specifications.

But I'm sure it's great stuff and comes well packaged.

 

[Pablo]

Strangely I can't find an Amsoil that meets or exceeds GL-5. Only "recommended for." I guess they don't meet or exceed API specifications.

But I'm sure it's great stuff and comes well packaged.

Is there an API GL-5 list?

 

[Navi]

A historical note. Ford used 80w90 for the front diff and 75w140 for the rear diff before 2015 but for fuel savings they went with 75w85.

Fords recent history with differentials is not good thus its a good idea to go 75w140 in the rear. As for the front at least 75w110.

Im not going to say Amsoil is the best but its better than the factory fill and better than Walmart. Its a good idea to use Amsoil for critical gearboxes.

 

[The Critic]

A historical note. Ford used 80w90 for the front diff and 75w140 for the rear diff before 2015 but for fuel savings they went with 75w85.

Fords recent history with differentials is not good thus its a good idea to go 75w140 in the rear. As for the front at least 75w110.

Im not going to say Amsoil is the best but its better than the factory fill and better than Walmart. Its a good idea to use Amsoil for critical gearboxes.

For light duty street use, it isn't going to matter.

If you were regularly towing at the maximum weight limit, it'd be a different story.

 

[Navi]

Im going to talk to a mechanic today about the front diff fluid and what would be preferred to put in there. 75w140 offers the most protection in the Amsoil lineup. In any event whether you choose 75w90, 75w110, 75w140 or even 80w90 it will offer more protection than factory fill.

If you said to me...hey I have a work truck in Phoenix or we pulling all the time...etc...my mind instantly goes to 75w140.

 

[johnmyster]

Fords recent history with differentials is not good...

I thought their reputation was Sterling.

I have some history with the 11.5 AAM, which for many years was specified 75w-90 of 75w-85. Plenty of those things get heavily loaded and aren't known for dying. It seems the OEMs reach for more viscous fluid for problem drivetrains but let's agree that no amount of special sauce is a fix for bad/undersized design or neglect.

On a related note, my 11.5 AAM has an established brand of "meets or exceeds GL-5", 75-140 in it. For a front dif that typically isn't used long enough to get above ambient, I couldn't care less.