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Eaton Gear Oil Recommendations for the Truetrac #3671680
03/20/15 02:48 PM
03/20/15 02:48 PM
Joined: May 2003
Posts: 772
Ohio
Brian Barnhart Offline OP
Brian Barnhart  Offline OP

Joined: May 2003
Posts: 772
Ohio
The G80 auto locker stopped locking in my 06 Sierra, so I just had an Eaton Truetrac installed. My initial impressions are very good (but very limited at this moment). It seems very smooth and both wheels hook up when needed.

I read through this earlier thread regarding fluid recommendations. Though the thread is somewhat old, the recommendations are still valid for the most part.

Here's what Eaton says today in the documents currently on their website:

Detroit Truetrac
A quality petroleum (mineral) based oil is recommended. Synthetic oils and friction modifiers should not be used, as they will decrease overall performance.

Detroit Truetracģ
What kind of oil should I use? Can I use synthetic?
Do I need friction additive/modifier?
Truetrac units perform best when using GL5 mineral /
petroleum based gear oil. Synthetic lubes are
discouraged. Do NOT use friction modifier additives or
lubes formulated with friction modifiers. See the
ďLubricationĒ section of this product manual for further
details and specifications.

Lubrication Specifications
Detroit Truetracģ
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.

I was told that mine was filled with Mobil 1 when they did the install. I'm planning an oil change in a month or so, and I plan to install a conventional mineral oil without limited slip additive at that time. Unfortunately it appears most of the "majors" now include LS additives in all of their gear oils now. It appears that many of the "store brand" gear oils still lack the LS additive, so I'll probably choose one from among them.

Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3671704
03/20/15 03:14 PM
03/20/15 03:14 PM
Joined: Oct 2007
Posts: 1,606
Oahu, Hawaii
wirelessF Offline
wirelessF  Offline

Joined: Oct 2007
Posts: 1,606
Oahu, Hawaii
It's probably saying syn is not recommended because most of them come with an LS additive that can affect the performance of the truetrac. There are a couple of syn gear oils without the LS additive such as Redline 75W90NS or Eneos 75W90.

Re: Eaton Gear Oil Recommendations for the Truetrac [Re: wirelessF] #3671748
03/20/15 03:44 PM
03/20/15 03:44 PM
Joined: May 2003
Posts: 772
Ohio
Brian Barnhart Offline OP
Brian Barnhart  Offline OP

Joined: May 2003
Posts: 772
Ohio
Looks like Redline has dropped their 75W90NS. Apparently their NS oil is now limited to one 75W140NS offering.

Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3671789
03/20/15 04:08 PM
03/20/15 04:08 PM
Joined: Jun 2005
Posts: 12,830
Santa Barbara, CA
bdcardinal Offline
bdcardinal  Offline

Joined: Jun 2005
Posts: 12,830
Santa Barbara, CA
Motorcraft 75W140 and 80W90 does not come with a friction modifier added. The 75w140 is a full synthetic fluid.


2014 Ford Mustang GT Track Pack
1995 Ford Mustang GT

Ford/Mazda Parts Counter
NRA Benefactor Member
Opinions expressed are my own.
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3671836
03/20/15 04:51 PM
03/20/15 04:51 PM
Joined: Aug 2012
Posts: 72
Nebraska
riff1006 Offline
riff1006  Offline

Joined: Aug 2012
Posts: 72
Nebraska
Mobil Delvac 75w-90 is synthetic GL-5 without LS additives. I'm putting some in my Tacoma this weekend.

Last edited by riff1006; 03/20/15 04:51 PM.

2013 GMC Sierra 2500HD-6.6L Duramax
2008 Ford Fusion-2.3L
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3671860
03/20/15 05:19 PM
03/20/15 05:19 PM
Joined: Sep 2013
Posts: 187
Edmonton, Alberta, Canada
CurtisB Offline
CurtisB  Offline

Joined: Sep 2013
Posts: 187
Edmonton, Alberta, Canada
While I cannot speak from experience for the Truetrac differential, the Detroit Locker carries the exact same lubricant recommendation from Eaton. I'm using Chevron Delo 80w-90 ESI gear oil (which is a GL-5 conventional lubricant) with my Detroit Locker and it's smooth as can be.

I did a significant amount of digging about on internet forums trying to figure out Eaton's peculiar oil recommendation, and the general consensus is synthetic oils cause the differential operation to be much rougher/louder than with conventional.

The simple fact that your installer is using Mobil 1 is a good indication that it probably does not matter at all whether you use synthetic or conventional. If you want my honest opinion, problem free operation of these things has everything to do with a proper install; as long as you are using a gear oil at the viscosity recommended by GM, and without included friction modifier you're in good shape.


2008 F150 XL 4.6L 2WD - FL820s, M1 AFE 0w20
2013 F150 STX 5.0L 4WD - FL500S, M1 5w20
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3671881
03/20/15 05:31 PM
03/20/15 05:31 PM
Joined: Oct 2004
Posts: 9,139
Cincinnati, OH, USA
bullwinkle Offline
bullwinkle  Offline

Joined: Oct 2004
Posts: 9,139
Cincinnati, OH, USA
I have one of those in my F-450 in my sig, just use any ordinary gear oil in the correct weight, it'll be fine. The shop that installed mine actually added LSD additive to it (even though I told them NOT to), but it still seems to work OK.


06 Ram 3500 CTD 4X4(FG Venturi), 93 GMC C3500 6.2, 89 F-450 7.3, 98 XJ 4.0(XG8A), 05 xB(XG3600), 18 Transit 3.7, 03 Merc Grand Marquis 4.6 2V(XG2)
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3671897
03/20/15 05:51 PM
03/20/15 05:51 PM
Joined: Jul 2014
Posts: 1,544
Paradise of Florida
Greasymechtech Offline
Greasymechtech  Offline

Joined: Jul 2014
Posts: 1,544
Paradise of Florida
Needs friction to work. Best to use a nonlsd gear oil.

Redline NS, Motul...and over the road truck gear oils are great choices. What weight do you require?


At what point should a lurker start posting :-)
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3672566
03/21/15 08:18 AM
03/21/15 08:18 AM
Joined: Feb 2008
Posts: 383
BC, Canada
marc1 Offline
marc1  Offline

Joined: Feb 2008
Posts: 383
BC, Canada
Originally Posted By: Brian Barnhart
Looks like Redline has dropped their 75W90NS. Apparently their NS oil is now limited to one 75W140NS offering.


Is this true? It is still on their website:

http://www.redlineoil.com/product.aspx?product=58304

I am asking because in my LS applications I prefer to buy the NS product and dial in the amount of additive required rather than using a premixed LS fluid. As well, several locking differential styles do not require LS additives so I hope the non-LS fluid market does not vanish.


2017 Tacoma SR5 4WD 24k km M1 EP 0w20 M1 EP Filter
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3673694
03/22/15 01:50 AM
03/22/15 01:50 AM
Joined: Mar 2006
Posts: 9,543
Pennsylbammyvania
dailydriver Offline
dailydriver  Offline

Joined: Mar 2006
Posts: 9,543
Pennsylbammyvania
Motul makes both a great full synthetic AND a mineral based gear oil without the friction modifiers.

Torco makes a great mineral based gear oil (RGO), I believe also without the additive. wink


2016 Ford Fiesta ST 17K miles
Ravenol REP 5W-30
Fram XG3600 filter
Ravenol MTF-2 in the IB6 transaxle
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: marc1] #3675057
03/23/15 07:40 AM
03/23/15 07:40 AM
Joined: May 2003
Posts: 772
Ohio
Brian Barnhart Offline OP
Brian Barnhart  Offline OP

Joined: May 2003
Posts: 772
Ohio
Originally Posted By: marc1
Originally Posted By: Brian Barnhart
Looks like Redline has dropped their 75W90NS. Apparently their NS oil is now limited to one 75W140NS offering.


Is this true? It is still on their website:

http://www.redlineoil.com/product.aspx?product=58304

I am asking because in my LS applications I prefer to buy the NS product and dial in the amount of additive required rather than using a premixed LS fluid. As well, several locking differential styles do not require LS additives so I hope the non-LS fluid market does not vanish.


Oops, my mistake. I looked for it under the Gear Oils for Differentials. It's listed among the Gear Oils for Manual Transmissions even though it is also suitable for differentials. I will definitely consider it for my Truetrac.

Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3676061
03/24/15 05:13 AM
03/24/15 05:13 AM
Joined: May 2007
Posts: 8,028
Indianapolis, IN
dnewton3 Offline
Global Moderator
dnewton3  Offline
Global Moderator

Joined: May 2007
Posts: 8,028
Indianapolis, IN
The TrueTrak is a helical gear LSD device. It does not have clutches; it relies on the CoF (co-efficient of friction) between the gears and the housing to initiate it's effect of bias drive. These units are delivered with a set bias from OEM and it cannot be changed. The clearances are very specific to these type units. If you use the wrong fluid, it will alter the CoF and the bias will not respond correctly. You should NOT use syn or a friction modifier additive, or a lube with FM already in it.

The Detroit Locker (same as a No-Spin) uses a spring loaded locking dog tooth system; it's not the same as the helical gear TrueTrac, but it does have the same fluid requirement.


For the TrueTrac use ONLY a GL-5 fluid that is NOT syn or FM modified. Be careful, because some dino gear oils still have FM in them. I would recommend a simple choice such as the W/M SuperTech GL-5 80w-90. Easy to get; meets the criteria.

These units are very reliable and have great longevity. They don't need anything special to survive; just the right fluid.


Sideline Q:
What happened to the G-80? Grenade itself? Not unheard of. That "M-Locker" is great in theory, but fails at times when put to hard use. The TrueTrac is a common "upgrade" for these units. Which axle do you have? AAM 11.5 in a HD, or a 1/2 ton?

Last edited by dnewton3; 03/24/15 05:17 AM.

The act of preventative maintenance, in and of itself, is FAR MORE important than brand/grade/base choices among lubes and filters.
- under maintaining something is akin to abuse/neglect; that can kill equipment by shortening the lifespan
- over maintaining something has never been proven to be anything but a waste of time and money
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: dnewton3] #3676245
03/24/15 10:32 AM
03/24/15 10:32 AM
Joined: May 2003
Posts: 772
Ohio
Brian Barnhart Offline OP
Brian Barnhart  Offline OP

Joined: May 2003
Posts: 772
Ohio
The G80 didnít grenade, but wouldnít drive both sides any longer. I didnít find any broken parts in my somewhat cursory inspection, so I suspect the small clutches were gone. As far as I can tell, it stopped locking after a few donuts in the snow. It had regular fluid changes and 108,000 miles on it. Itís a 8.6Ē in a Ĺ ton.

Iím very happy with this unit. Itís much nicer than the M-Lock. Iím fairly certain the installer filled it with M1 75W90, which is (obviously) synthetic, and has FM added. So Iím going to change it out soon.

My preference would be a non-synthetic 75W90 with no FM. I donít really want to give up cold flow and increase drag by using an 80W90 or 85W140 conventional. Including FMs in gear oils has become commonplace and itís getting hard to find anything other than house brand 80W90 without it. Some of the 75W90 gear oils marketed for OTR appear to lack FMs, but like their "automotive" counterparts, most are synthetic.

Re: Eaton Gear Oil Recommendations for the Truetrac [Re: dnewton3] #3676923
03/24/15 09:39 PM
03/24/15 09:39 PM
Joined: Feb 2008
Posts: 383
BC, Canada
marc1 Offline
marc1  Offline

Joined: Feb 2008
Posts: 383
BC, Canada
Originally Posted By: dnewton3
I would recommend a simple choice such as the W/M SuperTech GL-5 80w-90. Easy to get; meets the criteria.


Is this product void of LS additives? If so that is great. I used to use Castrol Hypoy C but I cannot find it anymore, I can only find the new bottles that infer there is an LS component in it.


2017 Tacoma SR5 4WD 24k km M1 EP 0w20 M1 EP Filter
Re: Eaton Gear Oil Recommendations for the Truetrac [Re: Brian Barnhart] #3677208
03/25/15 05:54 AM
03/25/15 05:54 AM
Joined: May 2007
Posts: 8,028
Indianapolis, IN
dnewton3 Offline
Global Moderator
dnewton3  Offline
Global Moderator

Joined: May 2007
Posts: 8,028
Indianapolis, IN
Yes - I believe the dino ST 80w-90 gear oil is devoid of any FM. I suspect that's true of the semi-syn gear oil as well, as they both mention "for top off of LSD" or something akin to that. The implication being that they have no FM, so they are not a replacement fill for LSD applications. (of course, you can use it and then add FM additive if needed; it's presumably not in the GL-5 bottled ST product).

I think the only product they offer with FM in it is their full-syn 140 grade; it does mention LSD application.

As always, check directly with them for yourself; don't take my word for it.

Last edited by dnewton3; 03/25/15 05:58 AM.

The act of preventative maintenance, in and of itself, is FAR MORE important than brand/grade/base choices among lubes and filters.
- under maintaining something is akin to abuse/neglect; that can kill equipment by shortening the lifespan
- over maintaining something has never been proven to be anything but a waste of time and money
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