Rear Diff Flud - Ford Truck Enthusiasts Forums

Notices
6.0L Power Stroke Diesel 2003 - 2007 F250, F350 pickup and F350+ Cab Chassis, 2003 - 2005 Excursion and 2003 - 2009 van

Rear Diff Flud

Reply

 
 
 
  #1  
Old 07-06-2017, 10:02 AM
akblackfoot's Avatar
akblackfoot
akblackfoot is offline
Elder User
Thread Starter
Join Date: Mar 2016
Posts: 518
akblackfoot is gaining momentum as a positive member of FTE.akblackfoot is gaining momentum as a positive member of FTE.
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?
 
Reply With Quote
  #2  
Old 07-06-2017, 10:09 AM
Blakshukvw
Blakshukvw is offline
Elder User
Join Date: Jul 2016
Location: Blue Springs, mo
Posts: 646
Blakshukvw has a good reputation on FTE.Blakshukvw has a good reputation on FTE.
You should be ok if it had modifier in it. The Amsoil is the same way. I personally use it in my truck's but I still add some modifier anyway. It won't hurt to add additional modifier.
 
Reply With Quote
  #3  
Old 07-06-2017, 10:41 AM
MisterCMK's Avatar
MisterCMK
MisterCMK is online now
Avid Winter Hater
Join Date: Mar 2003
Location: Rogers, MN
Posts: 23,944
MisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputation
If it isn't chattering there is no reason to add any.

Adding more will make the limited slip unit less effective.
 
Reply With Quote
  #4  
Old 07-06-2017, 11:32 AM
bismic's Avatar
bismic
bismic is online now
Post Fiend
Join Date: Nov 2003
Posts: 17,731
bismic has a superb reputationbismic has a superb reputationbismic has a superb reputationbismic has a superb reputationbismic has a superb reputationbismic has a superb reputationbismic has a superb reputationbismic has a superb reputationbismic has a superb reputationbismic has a superb reputationbismic has a superb reputation
From 50k miles on, I have uses the Mobil 1 Synthetic 75W-140LS also. Never have added extra friction modifier to it. 194k miles now, no issues.
 
Reply With Quote
  #5  
Old 07-06-2017, 12:30 PM
akblackfoot's Avatar
akblackfoot
akblackfoot is offline
Elder User
Thread Starter
Join Date: Mar 2016
Posts: 518
akblackfoot is gaining momentum as a positive member of FTE.akblackfoot is gaining momentum as a positive member of FTE.
Thanks everybody. I was pretty sure this was the case but just needed some confirmation from more knowledgeable people.
 
Reply With Quote
  #6  
Old 07-07-2017, 04:48 PM
Pest007's Avatar
Pest007
Pest007 is offline
Senior User
Join Date: Jun 2004
Location: Goodyear, AZ
Posts: 431
Pest007 is starting off with a positive reputation.
How much does it take to change? I'm needing to change mine and want to buy the upgraded Ford diff cover with the cooling fins
 
Reply With Quote
  #7  
Old 07-07-2017, 06:31 PM
akblackfoot's Avatar
akblackfoot
akblackfoot is offline
Elder User
Thread Starter
Join Date: Mar 2016
Posts: 518
akblackfoot is gaining momentum as a positive member of FTE.akblackfoot is gaining momentum as a positive member of FTE.
3.5 quarts or so. Got 4 and had some left over.
 
Reply With Quote
  #8  
Old 07-08-2017, 10:18 AM
amdriven2liv's Avatar
amdriven2liv
amdriven2liv is offline
I'm hitting easy street
Join Date: Nov 2009
Location: Southern, Washington
Posts: 6,358
amdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputationamdriven2liv has a superb reputation
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.
 
Reply With Quote
  #9  
Old 07-08-2017, 09:14 PM
Dr.Huxtable's Avatar
Dr.Huxtable
Dr.Huxtable is offline
Senior User
Join Date: Nov 2015
Location: Spartanburg, SC
Posts: 370
Dr.Huxtable is gaining momentum as a positive member of FTE.Dr.Huxtable is gaining momentum as a positive member of FTE.
Ugh this thread just reminded me I need to do this. Been putting it off because I wanna upgrade the cover at the same time. Money and time, two things there's never enough of!
 
Reply With Quote
  #10  
Old 07-09-2017, 08:12 AM
DSMMH's Avatar
DSMMH
DSMMH is offline
Posting Guru
Join Date: Jun 2006
Posts: 1,400
DSMMH has a great reputation on FTE.DSMMH has a great reputation on FTE.DSMMH has a great reputation on FTE.DSMMH has a great reputation on FTE.DSMMH has a great reputation on FTE.DSMMH has a great reputation on FTE.
I upgraded the diff cover several years ago. The new capacity is 6 quarts. I use Royal Purple 75W-140 and two years ago added AR9100. That took care of a chattering problem I had.

Ed
 
Reply With Quote
  #11  
Old 07-09-2017, 04:27 PM
akblackfoot's Avatar
akblackfoot
akblackfoot is offline
Elder User
Thread Starter
Join Date: Mar 2016
Posts: 518
akblackfoot is gaining momentum as a positive member of FTE.akblackfoot is gaining momentum as a positive member of FTE.
I have the Ford aluminum diff cover and it took less than 4 quarts so I'm sure it depends on which one you have.
 
Reply With Quote
  #12  
Old 07-09-2017, 06:14 PM
TooManyToys.'s Avatar
TooManyToys.
TooManyToys. is online now
Post Fiend
Join Date: Dec 2014
Location: Jersey Shore
Posts: 6,531
TooManyToys. has much to be proud ofTooManyToys. has much to be proud ofTooManyToys. has much to be proud ofTooManyToys. has much to be proud ofTooManyToys. has much to be proud ofTooManyToys. has much to be proud ofTooManyToys. has much to be proud ofTooManyToys. has much to be proud of
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.
 
Reply With Quote
  #13  
Old 07-10-2017, 10:29 AM
jlillie
jlillie is offline
Senior User
Join Date: Nov 2002
Location: Cape Coral USA
Posts: 236
jlillie is gaining momentum as a positive member of FTE.jlillie is gaining momentum as a positive member of FTE.
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.
 
Reply With Quote
  #14  
Old 07-10-2017, 02:59 PM
MisterCMK's Avatar
MisterCMK
MisterCMK is online now
Avid Winter Hater
Join Date: Mar 2003
Location: Rogers, MN
Posts: 23,944
MisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputationMisterCMK has a superb reputation
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.
 
Reply With Quote
  #15  
Old 07-10-2017, 03:14 PM
wedge542's Avatar
wedge542
wedge542 is offline
Elder User
Join Date: Jan 2007
Posts: 865
wedge542 is gaining momentum as a positive member of FTE.
Originally Posted by MisterCMK View Post
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.
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.
 
Reply With Quote

Thread Tools
Search this Thread
Quick Reply: Rear Diff Flud


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.