Changing Rear Differential Fluid
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Junior User
Joined: Mar 2020
Posts: 98
Likes: 0
From: Port Angels, WA
Changing Rear Differential Fluid
Ok so I think it's time to change the fluid in the rear end. I haven't really checked yet, but I think I have a 10 1/4 or 10 1/2 Sterling rear end and I think both of those call for 75W-140 full synthetic. Correct me if I'm wrong on that. I am also sure the rear end is limited slip so if all I have said is correct....how much friction modifier should I use? Everything I have read that I can find just says use some, but not how much. I am thinking about 4 oz. is that right?
Thanks
Thanks
Fleet Mechanic
Joined: Mar 2017
Posts: 1,365
Likes: 179
From: Phenix City, AL
I also went with the Mobil 1. I didn’t have to add any extra modifier for my LSD. I also went with a Lube Locker gasket and later version finned diff cover. My original cover was a rusted mess.
Lead Driver
Joined: Jun 2013
Posts: 5,647
Likes: 891
From: north of Minneapolis, MN
I used the Amsoil 75-140...I thought the additive was in there?
Fleet Mechanic
Joined: Jun 2015
Posts: 1,635
Likes: 564
I don't think it was...
Edit.. from amsoil brochure..."amsoil synthetic gear lubes do not require the use of this additive (slip lock). However, not all differentials respond the same and if chatter is noticed, the addition of amsoil slip lock will eliminate it".
I must have added as a precaution. No chatter to speak of lol.
FTE Leadership Emeritus
Joined: May 2014
Posts: 27,348
Likes: 5,941
From: Lake Hartwell, GA
I used Amsoil rear diff fluid as well and needed ~5oz of Motorcraft friction modifier to keep it happy.
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It's a Van Gogh
Joined: Feb 2010
Posts: 7,802
Likes: 1,333
From: Elk Grove, CA
This is the 08 and up finned aluminum cover Armylifer spoke of. OEM from Tasca and $120, tough to beat.
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Laughing Gas
Joined: May 2007
Posts: 793
Likes: 29
That cover is a perfect swap. Over time it will get a good layer of oxidation. Am not the best expert to tell whether the oxidation reduces (or by how much) its ability to radiate / transfer heat to air. Am considering getting another cover and coating it with a heat shedding ceramic coating. Then again, perhaps Ford added a protective layer since I bought mine.
Or, another way to go is that Banks just came out with a diff cover which reportedly puts all others to shame
Comes with AMOIL lube.
EDIT: Turns out that release Banks new cover is still pending and due this Summer.
Or, another way to go is that Banks just came out with a diff cover which reportedly puts all others to shame
Comes with AMOIL lube.EDIT: Turns out that release Banks new cover is still pending and due this Summer.
FTE Chapter Leader
Joined: Jan 2005
Posts: 13,106
Likes: 4,714
From: Henderson, NV
https://www.bankspower.com/i-2932-di...D7.3L%20DIESEL
Cross-Country
Joined: Feb 2007
Posts: 75
Likes: 2
WOW, I agree that is a nice cover. Very well thought out and engineered, with data to back it up. Just about perfect for on-road haulin.
I know he has been doing alot of research, development, and testing over the last 3-4 years.
The only con I can see is off-road use. Although the cover does not decrease ground clearance, the air flow splitter/spoiler wings on the lower right and left might have the tendency to get caught on stuff that might otherwise slip by around the pumpkin (I'm think tree stump or large rock).
However, it sure is nice to still see someone developing and producing a quality product.
I know he has been doing alot of research, development, and testing over the last 3-4 years.
The only con I can see is off-road use. Although the cover does not decrease ground clearance, the air flow splitter/spoiler wings on the lower right and left might have the tendency to get caught on stuff that might otherwise slip by around the pumpkin (I'm think tree stump or large rock).
However, it sure is nice to still see someone developing and producing a quality product.
Fleet Mechanic
Joined: Mar 2017
Posts: 1,365
Likes: 179
From: Phenix City, AL
Here’s my aluminum diff cover and fluid change parts list in case you are interested:
Ford 8C3Z-4033-A Differential Cover
Lube Locker Ford Sterling 10.25 & 10.5 Differential Gasket
5/16" Flat SS Washers Hillman Group 830504 x100
5/16"-18 X 1-1/4" FT SHCS x25
Mobil 1 102490 75W-140 Synthetic Gear Lube x4 quarts
Ford 8C3Z-4033-A Differential Cover
Lube Locker Ford Sterling 10.25 & 10.5 Differential Gasket
5/16" Flat SS Washers Hillman Group 830504 x100
5/16"-18 X 1-1/4" FT SHCS x25
Mobil 1 102490 75W-140 Synthetic Gear Lube x4 quarts
