Rear Diff Flud
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Joined: Mar 2016
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Rear Diff Flud
Change the fluid in my differentials a couple weekends ago. I used Mobile 1 Synthetic 75W-140LS in my rear diff. Said it has the friction modifier in it and I haven't noticed anything odd or out of the ordinary after changing it. Had some people claim you still have to add friction modifier or it will screw up the rear end. Any truth to that?
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More Turbo
Joined: Mar 2016
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I'm hitting easy street
Joined: Nov 2009
Posts: 6,395
Likes: 27
From: Central Oregon
I used the Valvoline oil for limited slip. Every thing was fine until I started pulling this trailer around the country. I had to add 1 bottle of fords additive. Just thought I should pass this along.
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Hotshot
Joined: Dec 2014
Posts: 17,823
Likes: 3,101
From: Jersey Shore
No matter the cover, the bottom of the fill port in the diff is the correct amount for coverage.
At 100k I ent no additive as y limited slip was limited no more. Didn't change by not using the additive. At some point I'll pull the clutches and replace.
At 100k I ent no additive as y limited slip was limited no more. Didn't change by not using the additive. At some point I'll pull the clutches and replace.
Mountain Pass
Joined: Nov 2002
Posts: 242
Likes: 8
From: Cape Coral USA
I just did mine. Got the aluminum cover, put a black paint job on it, with the stainless allen head bolts. Used Amsoil with most of a bottle of friction modifier, but the point i wanted to make is i also used a Lube Locker gasket which saved me from having to use permatex and waiting 24hrs before i could add the oil back. No leaks so far.
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
If you're going through the trouble of opening up the differential, you might as well toss a true trac in there and have a traction device that actually works and then never worry about friction modifier ever again.
Laughing Gas
Joined: Jan 2007
Posts: 883
Likes: 5
Do you have one in yours,it doing ok on the street or towing heavy, im installing clutches,side gears,spider and gears in mine now but with 340k guess its time.