Eaton Gear Oil Recommendations for the Truetrac

[Greasymechtech]

Clutches springs?
http://www.eaton.com/Eaton/ProductsServices/Vehicle/Differentials/detroit-truetrac/index.htm

Mack GO-J and GO-J+ are a pretty good list of gear oils, most without LS additives.

LSD additive for helical gear surface break-in polishing??

http://www.redlineoil.com/product.aspx?pid=41&pcid=4

 

[Brian Barnhart]

1 FMF,

From the content of your post, I believe you lack good understanding of Eaton's Truetrac particulars. The Truetrac is significantly different than diffs utilizing springs and clutch packs.

 

[1 FMF]

^^^ that is what i'm referring to, which is the design of the truetrac and torsen, where using any kind of GL-5 gear oil is fine. you don't have to worry about friction modifier, limited-slip additive or whatever you want to call the additive. it will not hurt the differential and it won't cause any noticeable difference in lockup performance.

as opposed to something like the auburn differential below, which has clutch packs under spring pressure. this is where you need the friction modifier in an oil to allow those clutch friction discs to slip smoothly when one wheel needs to spin at a different speed than the other. if my wording in previous post did not come across this or was ambiguous, sorry.

 

[1 FMF]

has friction discs like this, then needs the additive otherwise you might have problems turning where the clutches chatter when slipping.
and i have an 06 sierra 2500hd with the 11.5aam axle, also with a non-locking G80 diff. so i am somewhat familiar with eaton diffs particularly what it'll cost me to replace that pos g80.

 

[dailydriver]

Originally Posted By: dnewton3
Originally Posted By: dailydriver
I was just in NAPA, and they had a mineral based (white bottle) Valvoline 75W-90 right on the shelf.

I was not paying attention as to whether or not it had the friction modifier in it or not, but if it does not, that could be another fairly easy to get choice.

The Lakewood BFL (yellow label) is good stuff as well, but it definitely has the FM in it, so it's a no go for you.

Yes, most I know with a Truetrac say they are STRONG, quiet, and seamless/invisible in operation.
My only complaint with them (besides COA), is their lower bias than some other units out there (including some other Tosen/worm gear types), if one needs that.



Caution here; the white bottle has FM in it.
Check closely before using, as FM in the Truetrac is a BAD idea.
http://www.valvoline.com/pdf/high_performance_gear.pdf


Yes, I was NOT sure whether or not it had the added FM in it, why I put the disclaimer on this fluid.

 

[dailydriver]

If I had a Truetrac, my ratinale for NOT using a limited slip FM (or even a synthetic gear oil) would not be longevity, or any damage to the unit, but rather to NOT lessen the amount of bias even one little infinitesimal bit, since it already starts with lower bias than either the Quaife, or Torsen T2R units.

 

[dnewton3]

1 FMF

Eaton's very own tech info specifically warns against certain fluids with FM and/or syns when using the TrueTrac.

Additionally, our vaunted member (who has faded away due to other committments), Jim Allen, who is a noted technical automotive writer and avid 4x4 enthusiast with decades of experience on the "trail", also specifically warns against such fluids in the helical gear diffs.

Also, I have actually emailed them over this very topic, and received input as to why to NOT use syns/FM in this application. Syns and FM are tolerable, but they will most certainly alter the operation of the unit.

Detroit Truetrac®
High quality mineral or synthetic gear lubes are required for use in Detroit Truetrac differentials. Regardless of the lube type, always use a GL5 rated lube with the least amount of friction modifier. Mineral lubes lacking friction modifiers (limited-slip additives) were historically recommended for all Truetrac applications because friction modifiers can slightly reduce the bias ratio (limited-slip aggressiveness) of Truetrac differentials. However, to address the continually increasing power outputs of modern
powertrains, many vehicle manufacturers have switched to synthetic lubricants as a counter measure for increased axle temperatures and prolonged service intervals. In general, consult the vehicle owner's manual for the manufacturer's recommendations for lubrication type, weight and fill volume. This will ensure lube compatibility with the seal materials and bearings used in the axle. Eaton Performance technical support is available for any concerns in lube selection.
Taken from here; page 25 of the install/op manual:
http://www.eaton.com/Eaton/ProductsServices/Vehicle/Differentials/detroit-truetrac/index.htm#tabs-4



Yes - they do allow for the use of syns and FM. But they are not advisable nor desired. They are, shall we agree, tolerated in the application. They will, most assuredly, alter the bias of the LSD device, which relies on the CoF for operation and resultant application force. Will the device work with syns and FM additive? Yes. Will they work at their maximum efficiency as designed? No, they will not.


Why do we use lubricants? To reduce wear. To that end, if you can have a fluid that achieves the task, and do it for the least cost and least risk to performance, why not use that fluid? Looking at the SAE J2360 approved list, there are dino fluids that do meet the spec, that don't have FM, that are not synthetic. Why pay for a lube that will cost more and compromise the bias effect, when you don't have to? Any decent GL-5 dino non-FM fluid will work, and it will work with the maximum effect in the helical gear device.

 

[Brian Barnhart]

I ended up replacing the Mobil1 Truetrac fluid originally installed with SuperTech 75W90 Syn-Blend about 2 months ago. On the bottle, it implies that the SuperTech doesn't contain friction modifiers (top off for limited slip applications).

I do seem to hear some occasional clunking sounds from the rear now (such as in sharp turns on dry surfaces where the ground isn't flat, like a driveway/berm). Don't remember hearing much noise before the fluid change. The axle does seem to be hooked up most of the time (or at least anytime it's providing torque, as opposed to coasting), which is likely why there is more noise under certain conditions). I'll gladly take the little extra noise for better lock-up.

 

[dwaleke]

Just to update this thread. Autozone is changing over the labeling on their Coastal products to Autozone brand.

Bottles are the same and they imply that they are for top-off only of limited slip applications.

They had 75w90, 80w90, 85w140 on the shelf for $5.99 a quart.

 

[4WD]

I put Mobil Delvac Synthetic in my Eaton rear and put Mobil 1 of same 75-90 in front diff ...
The Mobil 1 makes specific mention of FM - the Delvac Synthetic 75-90 does not. It carries many OEM approvals ...

 

[MolaKule]

Originally Posted By: 4WD
I put Mobil Delvac Synthetic in my Eaton rear and put Mobil 1 of same 75-90 in front diff ...
The Mobil 1 makes specific mention of FM - the Delvac Synthetic 75-90 does not. It carries many OEM approvals ...


Mobil Delvac Synthetic would be my choice for HD TrueTracs.

We have to differentiate the friction modification (FM) chemistry that is used for anti-chatter in clutch type limited slip differentials and those used in Mobil Delvac Synthetic.

There are FM's in Mobil Delvac Synthetic but these FM's are for boosting MPG's. They are a different chemistry and should not interfere with the torque bias of the TrueTracs.

The FM's that are used for anti-chatter in clutch type limited slip differentials will change the torque bias in TrueTracs.

However, mineral oil based GL-5 gear lubes without the LSD additive will work, albeit within more narrow temperature margins.

 

[zeng]

Originally Posted By: dnewton3
Why do we use lubricants? To reduce wear. To that end, if you can have a fluid that achieves the task, and do it for the least cost and least risk to performance, why not use that fluid? Looking at the SAE J2360 approved list, there are dino fluids that do meet the spec, that don't have FM, that are not synthetic. Why pay for a lube that will cost more and compromise the bias effect, when you don't have to? Any decent GL-5 dino non-FM fluid will work, and it will work with the maximum effect in the helical gear device.


+100

But dino is viewed as 'evils' often times here ........... never mind it's positive attributes.

 

[dailydriver]

Originally Posted By: MolaKule
Originally Posted By: 4WD
I put Mobil Delvac Synthetic in my Eaton rear and put Mobil 1 of same 75-90 in front diff ...
The Mobil 1 makes specific mention of FM - the Delvac Synthetic 75-90 does not. It carries many OEM approvals ...


Mobil Delvac Synthetic would be my choice for HD TrueTracs.

We have to differentiate the friction modification (FM) chemistry that is used for anti-chatter in clutch type limited slip differentials and those used in Mobil Delvac Synthetic.

There are FM's in Mobil Delvac Synthetic but these FM's are for boosting MPG's. They are a different chemistry and should not interfere with the torque bias of the TrueTracs.

The FM's that are used for anti-chatter in clutch type limited slip differentials will change the torque bias in TrueTracs.

However, mineral oil based GL-5 gear lubes without the LSD additive will work, albeit within more narrow temperature margins.


THANK YOU for this info!!

 

[Powerstroke]

I've had the TrueTrac in the front and Detroit locker in rear of my '07 F-250 for 4 years now. Not a single oil related or mechanical issue. All 4 tires dig vigorously on any off road/trail adventures. I use the Amsoil 80w90 in the front and Amsoil SVG 75w110 in the rear. Even crossing a ditch at a angle, both wheels still get power in the front. Haven't had any issues with just "one wheel spin" . And the front end is just so heavy, I rarely lift a front tire off the ground.

TrueTrac is a tough, amazing positive limited slip unit. The unit for the Dana 60 has a high bias ratio, and most of the time it feels like a locker up front, trying to turn around trail curves and truck likes to plow straight.

Hard to believe a synthetic alters the bias ratio on the unit much at all.

 

[MolaKule]

Originally Posted By: Powerstroke


Hard to believe a synthetic alters the bias ratio on the unit much at all.


And what is interesting is neither Eaton nor any other Torsen style limited slip differential company will tell you how much differential bias there is between a mineral-oil based GL and a synthetic GL.

 

[dailydriver]

Originally Posted By: MolaKule
Originally Posted By: Powerstroke


Hard to believe a synthetic alters the bias ratio on the unit much at all.


And what is interesting is neither Eaton nor any other Torsen style limited slip differential company will tell you how much differential bias there is between a mineral-oil based GL and a synthetic GL.


Yes, I am starting to believe that they are all just like Tremec, and only suggest the ONE SINGLE (mineral based) fluid that they have actually tested in their units, and NOTHING ELSE, based ONLY on that.

 

[Jeff_in_VABch]

Assuming you are talking about the Eaton Trutrac, I have installed and/or used at least 10 of them. I currently have one in the rear end of my daily driver. That vehicle currently has Redline 75W140 in it and had Redline Heavy Shockproof oil prior to that. Both of these oils probably were not recommended for the Trutrac but the unit fully locked using these oils and is generating very little metal.

Generally, the Trutrac does not care what kind of oil is in the differential. No matter what the instructions say, they work fine with any oil. However, with a cheap oil, they will wear out quickly especially if the oil breaks down. When they wear, they start putting out lots of metal that ends up destroying the ring and pinion.

You should use the oil your differential and ring and pinion needs. That is the first priority.

As far as how much lockup you get, I doubt the oil even has any effect on that. Using the Heavy Shockproof (a moly goo), lockup was just as good as with any other oil. However some of the Trutracs never lockup well at all. One I put in a GM 8.5" was totally pathetic and had almost no effect.

 

[dailydriver]

What is the bias ratio of the Truetracs, 2:1, or even less than that?
Does it differ according to application (vehicle)??

 

[zeng]

Quote:
However, with a cheap oil, they will wear out quickly especially if the oil breaks down. When they wear, they start putting out lots of metal that ends up destroying the ring and pinion.

No, not cheap oil.I beg to differ.

Differentials do often get damaged/excessively worn with the use of gear oils that is :super expensive; and of super synthetic base stocks;super additive packages; super branded But too low and inadequate viscosity grade/KV@40*C-100*C.
JMHO

 

[Jeff_in_VABch]

Originally Posted By: zeng
Quote:
However, with a cheap oil, they will wear out quickly especially if the oil breaks down. When they wear, they start putting out lots of metal that ends up destroying the ring and pinion.

No, not cheap oil.I beg to differ.

Differentials do often get damaged/excessively worn with the use of gear oils that is :super expensive; and of super synthetic base stocks;super additive packages; super branded But too low and inadequate viscosity grade/KV@40*C-100*C.
JMHO

Daily Driver - The bias ratios vary by application. I believe I saw a tech document that outlined the info. But they dont really give a lot of info.

Zeng - Yep, they will [censored] out even with super expensive stuff. I think what usually happens is you get a new carrier and ring and pinion set at the same time. Usually the R&P is both new and in a higher numerical ratio (faster pinion speed). During break in the R&P gets super hot. If an owner/customer pushes it, say a highway trip on new R&P, that oil will [censored] out for sure. Then the diff oil isnt changed out after R&P break-in. It can all start an expensive chain of events.