Differential Fluid Question

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Swacer

Full Access Member
Joined
Dec 5, 2012
Posts
237
Reaction score
79
Location
PA
Can someone please correct me if I’m wrong, but does the 2014 use different differential fluid than the other years?

Looking at the supplement, it appears the front is 80w-90 and rear is 75w-85? Why is this different than the other model years?

Is this correct? I planned to use amsoil and they don’t even make a 75w-85.
 

Riddick

Full Access Member
Joined
Dec 1, 2015
Posts
291
Reaction score
191
Location
Texas
That’s what mine reads. Not knowing any better during my research when I changed mine, I went with Royal Purple 75w-140 and haven’t had one lick of problems.

FYI: Royal Purple has an additive already in it for the front dif friction modifier (along with other brands). Double check Amsoil before you go buy that. Many scientific sounding threads on here say you don’t need it.
 
OP
OP
S

Swacer

Full Access Member
Joined
Dec 5, 2012
Posts
237
Reaction score
79
Location
PA
That’s what mine reads. Not knowing any better during my research when I changed mine, I went with Royal Purple 75w-140 and haven’t had one lick of problems.

FYI: Royal Purple has an additive already in it for the front dif friction modifier (along with other brands). Double check Amsoil before you go buy that. Many scientific sounding threads on here say you don’t need it.

I found some old threads from 2014 detailing this concern. Took a while to find them, but was like 25 pages of discussion.

Appears that 75w-85 is a typo? This was confirmed by the Ford person that is on the forum. Apparently they all use 75w-140 in the rear.

I was thrown for a bit of a loop on this because 75w-85 is even lighter than I run in the back of my camaro, and I was like "that just doesn't make sense..."

I think the general understanding is 75w-90 (or 80w-90) with FM in front, 75w-140 in the rear without FM.

Am I on the same page as everyone else now?
 

Ruger

FRF Addict
Joined
May 16, 2011
Posts
9,194
Reaction score
8,263
Location
Northern Nevada
Yup, I remember that old thread. There was some initial confusion, but it was eventually sorted out.

I've used both Amsoil and Royal Purple with good results. The advantage of Royal Purple is availability. You can get it anywhere. O'Reilly's has it, and if they don't have what you need they're happy to order it for you and you don't pay shipping.

While you're under the truck, you would do well to change the fluid in the transfer case. This is actually easier than the differentials because Ford saw fit to equip the transfer case with a real, actual drain plug. Glory Be! What a concept! Call or visit your Ford dealer's parts counter, give them your VIN, and ask them what fluid is recommended for your rig. Some require Ford Transfer Case Fluid (which looks for all the world like transmission fluid), and others require gear oil.
 
Last edited:
OP
OP
S

Swacer

Full Access Member
Joined
Dec 5, 2012
Posts
237
Reaction score
79
Location
PA
Yup, I remember that old thread. There was some initial confusion, but it was eventually sorted out.

I've used both Amsoil and Royal Purple with good results. The advantage of Royal Purple is availability. You can get it anywhere. O'Reilly's has it, and if they don't have what you need they're happy to order it for you and you don't pay shipping.

While you're under the truck, you would do well to change the fluid in the transfer case. This is actually easier than the differentials because Ford saw fit to equip the transfer case with a real, actual drain plug. Glory Be! What a concept! Call or visit your Ford dealer's parts counter, give them your VIN, and ask them what fluid is recommended for your rig. Some require Ford Transfer Case Fluid (which looks for all the world like transmission fluid), and others require gear oil.

Is there a link to the instructions on how to replace the rear differential fluid? I was planning to put a new rear cover on. I saw some people say you had to suspend the rear end in the air, other say they did it with the truck just sitting in their driveway.

The transfer case was replaced shortly before I bought it, so I checked the fluid last fall, it was full and looked pristine. I'm going to have the dealer do the transmission and front diff because i don't have the patience lol
 

03Cobraraptor

Full Access Member
Joined
Oct 7, 2015
Posts
352
Reaction score
198
XY 75w140 QL Quantity: 3



Is what ford put in mind when rebuilding the rear differential under warranty!
Good luck
 

Ruger

FRF Addict
Joined
May 16, 2011
Posts
9,194
Reaction score
8,263
Location
Northern Nevada
Is there a link to the instructions on how to replace the rear differential fluid? I was planning to put a new rear cover on. I saw some people say you had to suspend the rear end in the air, other say they did it with the truck just sitting in their driveway.

The transfer case was replaced shortly before I bought it, so I checked the fluid last fall, it was full and looked pristine. I'm going to have the dealer do the transmission and front diff because i don't have the patience lol

There WAS a great write-up posted in June 2014 about the replacement of the factory differential cover with a Mag-Hytec cover. I wrote it and now I can't find it. You don't need to jack up the truck, but you will need to dismount the spare tire.

The hardest part is removing the factory cover because it's glued/sealed onto the differential with the most tenacious gasket compound I've ever encountered. I removed all the screws and pounded on that cover with every applicable tool I had and in every way possible, and it still wouldn't budge. I had to resort to the very careful use of a chisel, employing it in a way that I hoped would do minimal damage to the mounting surface on the differential, and even that was challenging. I don't know what Ford uses for gasket sealant in that application, but Gorilla Glue has nothing on them.
 

Riddick

Full Access Member
Joined
Dec 1, 2015
Posts
291
Reaction score
191
Location
Texas
There WAS a great write-up posted in June 2014 about the replacement of the factory differential cover with a Mag-Hytec cover. I wrote it and now I can't find it. You don't need to jack up the truck, but you will need to dismount the spare tire.

The hardest part is removing the factory cover because it's glued/sealed onto the differential with the most tenacious gasket compound I've ever encountered. I removed all the screws and pounded on that cover with every applicable tool I had and in every way possible, and it still wouldn't budge. I had to resort to the very careful use of a chisel, employing it in a way that I hoped would do minimal damage to the mounting surface on the differential, and even that was challenging. I don't know what Ford uses for gasket sealant in that application, but Gorilla Glue has nothing on them.

I referred to your post when I did mine. Just want to give a quick shout out and say thanks. If you all can find his post, refer to it! Only difference with mine was the cover practically fell off. You must have had a glue happy assembler on yours.
 

Ruger

FRF Addict
Joined
May 16, 2011
Posts
9,194
Reaction score
8,263
Location
Northern Nevada
I referred to your post when I did mine. Just want to give a quick shout out and say thanks. If you all can find his post, refer to it! Only difference with mine was the cover practically fell off. You must have had a glue happy assembler on yours.

Thank you, Mr. Riddick.
Most kind.
 
Top