Differential Fluid for Detriot Truetrac Ford 8.8

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Originally Posted By: Jim Allen
Not getting rid of my LE607 for the time being... e.g. you'll have to pry it from my cold, dead hands!


They only sell this stuff in 5 gallon pails minimum, right?
I was asking about the LE products a while ago as an alternative to the Torco and Schaeffer's dino gear oils.
 
I was looking through the warranty information on the truetrac. It states use gear oil speced by the manufacturer. I just what a straight answer about gear oil. I mean come on it's not a NASA shuttle launch. I wonder why Ford went from a 75w-90 to a 75w-140? I wonder if it was because of the newer clutch plates that they used in the new Mustang GT's. They are the same cltuches used in the 03-04 Cobra's. That is really the only change in the internal rearend except for the 31-spline axles (Previous gens had 28 spline on the Gt model).
 
This is what I received from Valvoline:


This what I wrote:

I am going to install a Detriot/Eaton Truetrac differential into the Ford Factory 8.8 rearend. Ford specs a Syn 75w-140 and Eaton recommends a dino gear oil. I emailed Eaton about the viscosity and type of oil. They responded says that that I should not use a synthetic gear oil. The answer given seemed generic, saying that they tested the Truetrac and it tested better with a dino gear oil. And that the synthetic wouldn't allow the diff to operate correctly and may make more noise with the syn. I just want what is best for the car. I have always used synthetic lubricants, I just don't see why this would create a problem nor think that dino gear oils can out perform a synthetic gear oil. Any advice/recommendation would be much appreciated. They also stated that the unit was R&D'd with Valvoline 75w-140 dino gear oil. Valvoline doesn't make a 75w-140 dino gear oil. What do you think I should use from the valvoline line-up?

Thanks


THIS WHAT WAS SENT TO ME:


You are exactly right. Valvoline doesn't make a conventional 75w140 gear oil. It is very hard to imagine a conventional (dino) oil outperforming a synthetic. Valvoline can only recommend what the actual Ford manufacture recommends for their rearend applications, which is a Synthetic 75w140 gear oil.
 
I am leaning toward using a conventional gear oil for the break-in, and then using a syn-blend or full syn 75w-140. Has anyone ever heard of a differential failure because of synthetic lubricants?
 
Originally Posted By: Jtgrant
I was looking through the warranty information on the truetrac. It states use gear oil speced by the manufacturer. I just what a straight answer about gear oil. I mean come on it's not a NASA shuttle launch. I wonder why Ford went from a 75w-90 to a 75w-140? I wonder if it was because of the newer clutch plates that they used in the new Mustang GT's. They are the same cltuches used in the 03-04 Cobra's. That is really the only change in the internal rearend except for the 31-spline axles (Previous gens had 28 spline on the Gt model).


ford went to the 140wt before the 05+ stangs came out. ive seen the tags on 99 mustang GTs.
 
Jtgrant: Methinks you are overthinking this. And perhaps the rest of us are too, as well as over-pontificating or getting lost in detail not really important to you.

Here's what we know:

1) Eaton recommends a conventional oil.

2) There are plenty of good conventional oils out there.

3) There are some documented problems using some (so far unknown brand) synthetics.

4) There are people out there running synthetics in Truetracs with no trouble, but again, we don't have a particular brand name that is known to be OK.

I ask you: What's wrong with running a top quality conventional oil if it's recommended by the differential manufacturer? At least until we can get you a "safe" brand of synthetic.
 
I haven't read all five pages of this post, but I've ran front and rear Truetracs in my Jeep for 8 years. The entire time has been with Amsoil 75W-90, and I wish I would have used 75W-140 in the rear for towing (not that it would have kept the D-35 from turning into a banana). The Truetracs have been absolutely great for the past 90K miles with the synthetic -- very smooth on the street, and work great off-road. Been over the Rubicon Trail and have run most of the 4+ trails of Moab. The D-35 rear axle has been a poor choice for Jeep to use, and I swapped in a 8.8 last year. I plan to re-gear to 4.10s this winter and will probably install another Truetrac differential. I will again use Amsoil -- 75W-110 in the front and 75W-140 in the rear. When we travel I pull a 2400# Scamp travel trailer.
 
Jtgrant: No apologies necessary... unless you keep posting the same question over and over like the guy on the HDEO forum. It was an interesting discussion that gave me a new research project!
 
Originally Posted By: Jim Allen
Jtgrant: No apologies necessary... unless you keep posting the same question over and over like the guy on the HDEO forum. It was an interesting discussion that gave me a new research project!


AGREED!!
Also, I have a personal interest since even though I don't own a True Trac now. If my Eaton Posi ever gives up the ghost my choices are either an Auburn Racer's diff or an uber-biased True Trac (if they would build one for me).
So I followed this thread with much interest, as I would like to run a synthetic in a Torsen type diff IF I could.
 
Then I have decided to break the diff in on dino 85w-140 and I already have several quarts of Redline 75w-140. I will refill with that after 500 miles. Thank you.
 
Jtgrant: Let us know if you have any oddball symptoms with the Redline. it would be nice to make a list, however anecdotal, of oils that perform well or poorly in the Trutrac.
 
Well I installed the new FRPP gear and the Trutrac on Saturday, the pattern was spot on. Both the drive and coast sides looked great, however I do have a slight whine on decel from 45-55 mph. Backlash was set to .010 (specs are .008-.012) It has been getting quieter everytime I drive it. I filled it with conventional Valvoline 85w-140 with a bit of friction modifier. (According to RL it also lowers operating temps and is good for break-in.) I first ran the car on the lift for 10 minutes unloaded. Allow it to cool for 30 min. I then drove the car from approx. 30 miles and allowed it to cool over night. I repeated this 3 times. I have decided to go 500 miles, drain and refill with Redline 75w-140 since I alreay have some laying around.
 
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Why would a helical diff not be able to use synthetics?

Here's some interesting Torsen/helical info
http://www.torsen.com/fsae/fsaefaq.htm
# 19 - Using less viscous oil will also raise TBR. A more viscous fluid will lower it. If you are changing the oil, be sure that you still use a GL-5 specification lubricant.
# 8 - A GL-4 or GL-5 gear oil is required by Torsen Type 1 units. This oil provides high-pressure additives needed to prevent the oil from breaking down under the extreme conditions generated by the tooth mesh. A 75W-90 is recommended, but higher or lower viscosities can be used if they meet GL-4 or GL-5 specification.
 
Jtgrant: Congrats. Hope you like yours as much as I like mine. You are a lot gentler than I was. I went out and towed 30 ton grain trailers after installing mine!

gtx510: If you read the entire thread, you will see the answer to that was thoroughly debated. Eaton/Detroit has noted numerous problems using certain synthetics. We are not sure exactly which synthetics... they ain't talkin' 'bout that... but we know that one of them is whatever Ford uses for a factory fill in the latest trucks. We also know that some syns do just fine. Jtgrant will be field testing Redline for us and Sven gives us a thumbs up on Amsoil.
 
Hey folks, I’m kinda a lurker here and I have a question that no amount of searching can answer. Sorry if I’m resurrecting an old thread but several emails and phone messages to Eaton have gone un-answered. AND the contributing folks in this thread appear very knowledgeable.

I recently installed a new Eaton Posi LSD in my car along with a AAM gearset. After searching gear fluids here on BISOG, I gave the shop that did the work a gallon of Schaefer’s #267 to use. They did not use it. They instead used GM fluid and LSA.

I consider the rear “broken in” now as it’s been several weeks and this is a daily driver. I’d like to put in the #267. As I understand it, #267 is a blended synthetic and has moly lube in it. HOWEVER Eaton’s own website says to use a API GL-5 fluid which #267 meets.

Has anybody used this fluid with this differential? Can I/should I use it?

Thanks!
 
Originally Posted By: Paul_Bell
Hey folks, I’m kinda a lurker here and I have a question that no amount of searching can answer. Sorry if I’m resurrecting an old thread but several emails and phone messages to Eaton have gone un-answered. AND the contributing folks in this thread appear very knowledgeable.

I recently installed a new Eaton Posi LSD in my car along with a AAM gearset. After searching gear fluids here on BISOG, I gave the shop that did the work a gallon of Schaefer’s #267 to use. They did not use it. They instead used GM fluid and LSA.

I consider the rear “broken in” now as it’s been several weeks and this is a daily driver. I’d like to put in the #267. As I understand it, #267 is a blended synthetic and has moly lube in it. HOWEVER Eaton’s own website says to use a API GL-5 fluid which #267 meets.

Has anybody used this fluid with this differential? Can I/should I use it?

Thanks!


If it's an Eaton carbon fiber clutchpack Posi (and NOT a True Trac helical gear type diff), I would NOT use anything with moly in it!!!
31.gif

According to the members on here it will not only nullify the actions of the diff (making it act as an open diff), but it will 'plate' itself onto the clutchpacks making it impossible to get rid of without a total disassembly/rebuild of the brand new Posi.
crazy2.gif


I have this Posi in my car, and up until recently I would have suggested to not even use a synthetic gear oil in it (as the Eaton techs warn/claim), but I have been using Red Line (with the friction modifier already added) along with 4 ounces of the Motorcraft XL-3 L.S. additive as well, and it has been absolutely FINE for about 5 months now.

Schaeffers makes some phenomenal gear oils, I would just try and find one sans any moly compounds.
wink.gif


Oh yeah, and
welcome2.gif
!!
 
Very well then. This IS a diff with carbon fiber clutch packs.

I'm glad the installation shop followed Eaton's instructions although in all likelyhood they have no clue why Eaton specifies not to use a synthetic.

Interesting though, Eaton does not state anywhere to not use a lube with moly.

I suppose when it's time for a fluid change I'll look at Redline or Torco.

Thanks for the info!
 
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