Differential Fluid for Detriot Truetrac Ford 8.8

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Thanks for all the info Jim. I got an education!

BTW, if you'd like to move on to synthetics sooner rather than later, I'll take all the LE 607 off your hands. Let me know via PM if you're interested.
 
What are some really good dino gear oils? The thing that really sucks is that I can get BMW gear really cheap(Castrol). I responded to the email sent to me from Eaton. I will post there response.
 
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Salesrep could chime in here about Schaeffer gear oils. I believe their #267 is a good SAE 90 dino, but it has moly as an EP additive. It sounds like Eaton doesn't like moly.

Lubrication Engineers used to make LE 607 (SAE 90), but it has been replaced with their DUOLEC 1604 and 1605 (SAE 90 and SAE 110) now. It is a synthetic blend with a different EP additive and tackifier.

From my research and past experience, LE and Schaeffers seem to take their gear oils seriously and make great products. I prefer the LE due to the lower pour point (-11F vs 5F).
 
To further confuse the issue, historically the Ford 8.8 and 9 inch rear ends had a "high offset" pinion gear, and required a special gear lube to prevent early wear. Typically that was a GL-6 rated oil, now obsolete

The API has this document about various GL ratings, including GL-6

http://www.api.org/certifications/engineoil/pubs/upload/1560.pdf

Here in Canada, Esso still makes a GL-6 gear oil, and it is very reasoably priced

http://www.esso.ca/Canada-English/Files/Products_Lubes/IOCAENCVLESEsso_GO_GX_EX.pdf

I have a 1984 Ford F-150 at my hobby farm, which I use as a trip-to-the-dump and plow vehicle. It has a 8.8 rear end, and around 5 years ago I put in a locking rear axle. I went with the PowerTrax LockRight

http://www.powertrax.com/lockright.html

This is a very simple unit to install, and always keeps the rear axle locked until making a tight turn. Then the inside wheel hops and a "click-click-click" noise from the axle. That said, I highly recommend it

I went with Esso Gear Oil GX Extra to keep the GL-6 requirements for the Ford 8.8. I also put on a Mag Hytec cover, makes it super easy to service. The magnets on the dipstick and drain plug really do work!
 
I heard back from my Eaton contact. Here's what he says: The Truetrac will sometimes make screeching noises with some synthetics. It goes away with a refill of dino oil. He can't give me any specifics on which oils, but it occurs reasonably often with factory fill syns. The Truetrac is used in several OE trucks, Ford for one, and it's a little bit of a warranty issue right now. He doesn't know exactly why. Some syns seem to be fine (or at least people aren't calling back to complain). I suspect it could be a quality issue between some brands. I'm not sure if Eaton has even really studied why. It's much simpler to shotgun it and just recommend a dino oil. I guess a guy could try a synthetic and if there was no screeching, drive off happily into the sunset. If she makes noise, I guess you'd have to do an oil change. I've got a few other feelers out on this and if they bear fruit, I'll pass it along. All I know for sure at this point is that LE-607 doesn't make mine screech for mercy!
 
Originally Posted By: Jim Allen
I heard back from my Eaton contact. Here's what he says: The Truetrac will sometimes make screeching noises with some synthetics. It goes away with a refill of dino oil. He can't give me any specifics on which oils, but it occurs reasonably often with factory fill syns. The Truetrac is used in several OE trucks, Ford for one, and it's a little bit of a warranty issue right now. He doesn't know exactly why. Some syns seem to be fine (or at least people aren't calling back to complain). I suspect it could be a quality issue between some brands. I'm not sure if Eaton has even really studied why. It's much simpler to shotgun it and just recommend a dino oil. I guess a guy could try a synthetic and if there was no screeching, drive off happily into the sunset. If she makes noise, I guess you'd have to do an oil change. I've got a few other feelers out on this and if they bear fruit, I'll pass it along. All I know for sure at this point is that LE-607 doesn't make mine screech for mercy!


The bold above is exactly what some believe is the case with Tremec's making synthetics verboten in their T56 transmission. Some think it's just because they are too lazy/harried to go and test all of the available synthetics in their transmission. Who knows??

BTW; GREAT explanatory post on the operation of the True Trac (and most other Torsen type diffs).

One more suggestion for very good dino gear oil; Torco RGO. It is also reasonably priced, although hard to find on the shelf, but is readily available via mail order (just like the excellent Schaeffer's product).
 
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Originally Posted By: artificialist
GL-6 is sold by some speed shops. Richmond Gear is the brand.


Yikes, that price is almost $6/litre more than I paid for my Esso GX Extra 75W-90 in a 20 litre pail

Of course, there isn't much application outside of Ford 8.8 and 9 inch rear ends. Here in Canada, the GX Extra with GL-6 rating is still popular with loggers and some heavy equipment operators
 
Heard back again from Eaton, I asked a few more questions such as: What was the gear oil in the R&D stage of the unit and why they were pushing dino over a synthetic. Here is the answer that I received:

"The oil used in developing the Truetrac was always mineral based and usually a multi-weight product like a 75w-140 Valvoline.
Although synthetics provide better wear under a cruise type situation, they don't provide 'shear' or 'crush' strength required during high performance applications. Synthetics are mainly used for fuel economy purposes, not performance. One of our big customers, Drive Train Specialists in Michigan, did testing with GM regarding gear oil temp and wear. They tested 3 different setups; 1 with straight synthetics, 1 with straight synthetics and a finned alum cover and 1 with straight 90 weight mineral based gear oil. There tests showed that although the oil in the synthetics was cooler, the differential itself was hotter. The oil shed the heat but it had nowhere to go but sink into the diff and housing. Overall, the mineral oil based differential was cooler than the other 2 synthetic units. The tests placed the oil based unit 1st, the finned synthetic unit 2nd and the synthetic with a standard cover 3rd.
The testing above is why we recommend standard gear oil over synthetics. The Truetrac operates on gear separation forces and clearances are very important. The additional heat and less oil 'cushion' caused by synthetics can prevent the Truetrac from operating properly.
Our dealers have also mentioned how the industry has changed in the last 20 years. 20 years ago they rarely did differential work unless it was to do a gear change or a differential upgrade. Today, they work on rearends everyday, replacing gears and differentials with less than 100,000 miles. In their opinion, the difference between yesterday and today, is the widespread use of synthetic oils."
 
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Originally Posted By: Jtgrant
Our dealers have also mentioned how the industry has changed in the last 20 years. 20 years ago they rarely did differential work unless it was to do a gear change or a differential upgrade. Today, they work on rearends everyday, replacing gears and differentials with less than 100,000 miles. In their opinion, the difference between yesterday and today, is the widespread use of synthetic oils."


People today go further into the wood, deeper into the mud, haul/tow heavier, longer distance, and a lot of them use dino oils. Manufacturers specify synthetic oil to handle the extra stress being placed on the vehicles. The extra stress is what going to break the vehicle, not synthetic oils. A new 1/2 ton pickup today can tow 10K the same as a 1 ton truck 10 years ago.
 
"oil shed the heat but it had nowhere to go but sink into the diff and housing."

Huh?: And that made synthetic bad? Oil conducts and convects heat, it does not shed heat. Had the better heat conduction of the synthetic not conducted heat away sooner, the diffy would have failed sooner.

So, did the test include thermocouples in the oil and the housing to show this was the case??? I don't buy this explantion.
 
That, plus engine torque has risen quite a bit, too.

The other thing I read, was that more aerodynamic vehicles have less air going under the vehicle, and therefore less cooling of the rear axle.
 
heyjayman: A minor correction to your post above. The Ford 8.8 is not really a high offset diff. It has a 1.50 inch hypoid offset, identical to the Ford 9.75, 10.25 and 10.50, the GM/Saginaw 6.5, 7.5, 7.63, 8.0, 8.2, 8.25, 8.4 (55P),8.5, 8.6, 8.875 (12-bolt), 9.25, H-033, H-052, H-072, 9.5, 10.50, the AAM 9.25 front, the AMC-15 and AMC-20, the Chrysler 8.25, 8.35 and 8.75, the Dana 35, Dana 44, Dana 45 and Dana 50. The only diffs that could be called high offset, were the Ford 8.0, 9.0 and 9.38 dropouts at 2.38 inches. You could also call the modern AAM 10.50 and 11.50 (used in GM and Dodge pickups) diffs "high" because they are at 2-inches of hypoid offset. Close contenders could be the old Dana 53 at 1.6 in., the old Buick 9.3 at 1.75-in and the Chrysler 9.25 at 1.85-in.
 
Jtgrant: You were talking to my contact at Eaton! We had an hour long discussion over this and much of what you told posted was exactly what he told me. I got a little more detail and was able to ask questions, but you posted the gist.

Mola: I am trying to track down the source of the GM test that was mentioned. I think there's something to this but it was explained/interpreted by people that really don't know lubricants very well. I will try to get more detail and share it. Much of this "anti" synthetics seems to come anecdotally from racing circles. Here's the gist:

"Many race teams using synthetics have had premature gear failures. Those that use mineral based oils or blends don't. The only teams that have good luck using syns are those that have rear axle coolers."

While not a direct quote, those are the general reports from Toms Differentials and Drivetrain Specialists, and apparently also from Strange Engineering. There apparently is a recent article in a hot rod magazine on this topic that I am trying to track down. I do not understand the methodology here, I merely report what my sources tell me. The other anecdotal report is that high miles, hard worked R&Ps that have used syn for long periods, when examined, have a polished or chromed appearance and are worn sufficiently that a pattern cannot be read. A gearset operated the same way that has used a mineral oil long term has more gray color, less wear and a pattern can be read even on a high miles unit.

I do not know the whys of this but I trust the reports of these people. Even if they don't know exactly why it's happening, it makes me listen and try to figure out the wherefores and the whys. They don't have a bias against anything, it simple observation of cause and effect evidence that leads them that way. Some will not warranty their race axles if syns are used because they have seen too many failures. I still think it may have something to do with particular brands of synthetics, but that's information they aren't giving... either they don't want to be quoted dissing some brand, or they don't know. Could be a little of both, from my reading between the lines.
 
Originally Posted By: Jim Allen
heyjayman: A minor correction to your post above. The Ford 8.8 is not really a high offset diff.


Looks like my source has fed some incorrect information. Thank you for the correction

So it looks like I have no benefit running Esso Gear Oil GX Extra in my 1984 Ford 8.8 axle? At least the price is reasonable
 
Originally Posted By: Jtgrant
What should I use?


I would try to pry some of that LE 607 (dino) away from Jim Allen. Or, have a look at LE 1605 or 1606 (syn blend).
 
If I am going to use conventional gear oil, I would like to use something that I can get local. I saw Rotella gear oil in Walmart 80w90 and 85w-140, and AAP has the valvoline gear oil in conventional and syn blend. How is the Rotella compared to valvoline?
 
Jtgrant: My advice is to stick with a conventional oil to give your Truetrac what it likes best. If we discover something in the meantime, you can always change at a later date. As to viscosity, if you are not going to tow a lot or engage a lot of stoplight racing, I'd recommend sticking with an 80W90. Reserve the 85W140 for those two situations because it may cost you a little fuel economy. The Rotella looks good on paper and Shell has a better rep than Valvoline.

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

In the meantime, check out:
techarticles/drivetrain/129_0607_1986_ford_f250_hd_towing_axle/index.html>
 
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