Notices
1999 - 2003 7.3L Power Stroke Diesel  
Sponsored by:
Sponsored by: DP Tuner

Rear Diff fluid

Thread Tools
 
Search this Thread
 
Old Oct 6, 2006 | 08:57 AM
  #1  
powerstrokin007's Avatar
powerstrokin007
Thread Starter
|
Senior User
Joined: May 2006
Posts: 316
Likes: 0
From: Elmendorf AFB, Anchorage
Rear Diff fluid

Since I have about 50,000 miles on my truck i'm going to change the rear diff fluid. Does anyone recommed any particular fluid? I always used some off the wall 90w. What about a limited slip additive? Anything good?
 
Reply
Old Oct 6, 2006 | 09:28 AM
  #2  
Kwikkordead's Avatar
Kwikkordead
Fleet Owner
Shutterbug
Liked
Loved
Community Favorite
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
For my open diff I use Redline Shock Proof Heavy gear oil. I used it to quiet down a clunky rear end in my '91 F-250. It would give a heavy knock sound at the start of every accelloration from a stop light. After changing the rear end oil for the Shockproof it never knocked again.

http://www.redlineoil.com/products_g...6&categoryID=6

There is a lot of other choices from them as well.
 
Reply
Old Oct 6, 2006 | 09:33 AM
  #3  
RAMPAGE_F350's Avatar
RAMPAGE_F350
Posting Guru
Joined: Aug 2005
Posts: 1,768
Likes: 1
From: Central Alabama
I use Royal Purple 75W140 gear oil in the rear diff and it already has the limited slip additive in it.
 
Reply
Old Oct 6, 2006 | 09:58 AM
  #4  
herman2001's Avatar
herman2001
Junior User
Joined: Sep 2006
Posts: 52
Likes: 0
I changed mine last month when the rear diff cover rotted off... I just put in delo 75w90 and no problems so far
 
Reply
Old Oct 6, 2006 | 10:33 AM
  #5  
KrenzyRyan's Avatar
KrenzyRyan
Elder User
Joined: May 2006
Posts: 679
Likes: 0
From: Mesa, AZ
im using 75w140 mobil
 
Reply
Old Oct 6, 2006 | 12:08 PM
  #6  
Fat Diesel's Avatar
Fat Diesel
Logistics Pro
20 Year Member
Liked
Loved
Community Favorite
Joined: Aug 2005
Posts: 3,884
Likes: 180
From: Morgan Hill, CA
Club FTE Silver Member

If you have a limited slip diff, you want to use 75w140 SYNTHETIC. If you buy Red Line, don't buy the "LS" stuff. Some trucks require the friction modifier with some oils, some don't. Friction Modifier is $5 for a small bottle at Ford.
 
Reply
Old Oct 6, 2006 | 07:29 PM
  #7  
magnum300's Avatar
magnum300
Senior User
Joined: Jun 2004
Posts: 391
Likes: 0
From: west MI
I put Royal Purple in mine
 
Reply
Old Oct 6, 2006 | 09:49 PM
  #8  
2002f2507.3LPS's Avatar
2002f2507.3LPS
Senior User
Joined: Sep 2006
Posts: 484
Likes: 0
From: CT
how do u know if u have the limited slip diff?
 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

Top 10 Fords at 2026 Carlisle Ford Nationals

 Joe Kucinski
story-1

3 Best / 3 Worst Parts of Modern Ford Ownership

 Brett Foote
story-2

10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

 Pouria Savadkouei
story-3

Every 2026 Ford Engine Explained

 Brett Foote
story-4

10 Ugly Ford Trucks That We Still Kinda Love

 Joe Kucinski
story-5

10 Things Every Truck Owner NEEDS (2026 Edition)

 Michael S. Palmer
story-6

Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

 Verdad Gallardo
story-7

Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

 Joe Kucinski
story-8

2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

 Brett Foote
story-9

Top 10 Ford Truck Tragedies

 Joe Kucinski
Old Oct 7, 2006 | 01:12 PM
  #9  
powerstrokin007's Avatar
powerstrokin007
Thread Starter
|
Senior User
Joined: May 2006
Posts: 316
Likes: 0
From: Elmendorf AFB, Anchorage
Hadn't check yet. Just another question to ask if I do.
 
Reply
Old Oct 7, 2006 | 06:01 PM
  #10  
magnum300's Avatar
magnum300
Senior User
Joined: Jun 2004
Posts: 391
Likes: 0
From: west MI
Originally Posted by 2002f2507.3LPS
how do u know if u have the limited slip diff?
Go to the super duty forum and the read first 99-04 FAQ's, vin and tag decoder some people will have that code on the door piller sticker, for mine and others do not have this so you have to look at the tag on the differential cover if it has an L in it you have limited slip, or find a gravel road and punch it if you leave 2 burnout marks you have limited slip

Could someomne chime in on why some have the code on door sticker and others do not
 
Reply
Old Oct 7, 2006 | 06:21 PM
  #11  
2002f2507.3LPS's Avatar
2002f2507.3LPS
Senior User
Joined: Sep 2006
Posts: 484
Likes: 0
From: CT
well one tag said this on it. ( S 409 H ) below that on the same tag it said this ( L 73 10 5 1K 17 )

the other tag just said ( 75 w 140 synth oil only. ) wich im sure is just the oil to refill the rear end with.
 
Reply
Old Oct 7, 2006 | 08:14 PM
  #12  
powerstrokin007's Avatar
powerstrokin007
Thread Starter
|
Senior User
Joined: May 2006
Posts: 316
Likes: 0
From: Elmendorf AFB, Anchorage
Useful information. On my sticker it has D1 and when you look it up it's a 3.73 limited slip. Thanks.
 
Reply
Old Oct 7, 2006 | 08:52 PM
  #13  
magnum300's Avatar
magnum300
Senior User
Joined: Jun 2004
Posts: 391
Likes: 0
From: west MI
Originally Posted by 2002f2507.3LPS
well one tag said this on it. ( S 409 H ) below that on the same tag it said this ( L 73 10 5 1K 17 )

the other tag just said ( 75 w 140 synth oil only. ) wich im sure is just the oil to refill the rear end with.
You have a 3.73 limited slip
 
Reply
Old Oct 7, 2006 | 09:00 PM
  #14  
Uzumati's Avatar
Uzumati
Post Fiend
Joined: Jun 2006
Posts: 5,497
Likes: 7
From: Central, Al
Originally Posted by herman2001
I changed mine last month when the rear diff cover rotted off... I just put in delo 75w90 and no problems so far
Unless you have a different rear end the 75W90 is for the front and the 75W140 is for the rear
 
Reply
Old Oct 8, 2006 | 01:49 PM
  #15  
powerstrokin007's Avatar
powerstrokin007
Thread Starter
|
Senior User
Joined: May 2006
Posts: 316
Likes: 0
From: Elmendorf AFB, Anchorage
Originally Posted by amiller93
Unless you have a different rear end the 75W90 is for the front and the 75W140 is for the rear

Now with that fluid, what outside temp is it good for? Just wondering if it will hold up to the temp in Anchorage. Last year it got to -25 degrees outside.
 
Reply



All times are GMT -5. The time now is 10:56 PM.

story-0
Top 10 Fords at 2026 Carlisle Ford Nationals

Slideshow: Top 10 Fords at 2026 Ford Nationals

By Joe Kucinski | 2026-06-09 11:10:08


VIEW MORE
story-1
3 Best / 3 Worst Parts of Modern Ford Ownership

Based on years of owning multiple modern Ford products.

By Brett Foote | 2026-06-09 10:53:36


VIEW MORE
story-2
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

SPONSORED: From muddy boots to rain-soaked cargo, these upgrades address some of the most common frustrations Ford truck owners face every day.

By Pouria Savadkouei | 2026-06-08 18:50:34


VIEW MORE
story-3
Every 2026 Ford Engine Explained

Here's everything you need to know about every Ford engine available for the 2026 model year.

By Brett Foote | 2026-06-05 12:58:01


VIEW MORE
story-4
10 Ugly Ford Trucks That We Still Kinda Love

Slideshow: 10 ugly Ford trucks that we still kinda love.

By Joe Kucinski | 2026-06-03 09:51:16


VIEW MORE
story-5
10 Things Every Truck Owner NEEDS (2026 Edition)

Slideshow: the best gifts for dads & grads

By Michael S. Palmer | 2026-06-03 15:43:58


VIEW MORE
story-6
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-06-03 11:38:36


VIEW MORE
story-7
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Slideshow: 10 most expensive Ford trucks ever sold on Bring a Trailer.

By Joe Kucinski | 2026-05-27 16:24:34


VIEW MORE
story-8
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Here's everything that has changed for the latest model year.

By Brett Foote | 2026-05-27 16:17:28


VIEW MORE
story-9
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE