Maybe some whales had a low sperm count.

 

No way to tell - mabey the factory worker screwed up ?

1. They should not chatter with the factory oil and 1 bottle of GM additive.
2. They should not chatter with most synthetics and no additive at all.
3. If they chatter with a synthetic - add one additive.
4.If that does not work - suck it out and try the stock fluids.
5. If it still chatters with all GM fluids - take it apart.


-W

 

Like I've said, there's a zone between driveability and limited-slip (positraction) effectiveness. Some of you chemist have eliminated bump and chatter with the use of synthetics (some tried it with and some without the additive). But how do you know what impact the synthetic has on the limited slip functionality? Did you, as the service manual specifies, test the "slippage" with a torque wrench?

Why not do what the GM and Eaton engineers recommend, which is use a conventional / mineral gear lube and 4 oz. of the GM additive? They know where the "zone" is and how to achieve it. In fact, all the limited slip carrier manufacturers recommend against the use of synthetics, Eaton, Auburn, and Dana/Spicer, for use with their LS carriers.

Do you know something they don't?

 

No offence Mr. Blue, but you're misrepresenting the Eaton verbage to strengthen your point.

From Eaton's FAQ - "Eaton Posi" section:

Q: What kind of oil should I use? Can I use synthetics? Do I need a friction additive/modifier?
A: Eaton Posi units perform best when using GL4 (or better) mineral/petroleum based gear oil. A four ounce bottle of friction additive/modifier is also necessary for optimum performance.

Eaton DUCKS THE SYNTHETIC QUESTION ENTIRELY!??
They tell us what they like - and refuse to comment on synthetics in thier Posi FAQ. Nowhere, do they "recommend against" as you state.

So far all we "know that they don't" is what they havn't told us - which is nothing at all. You're guessing as to Eaton's position just as much as the guy who's trying to play chemist to find a good synthetic combo.

I've postulated that they "don't recommend" because they haven't tested too much at all - at least not enough to have a position. There are too many varieties of synthetics and additives to waste **time and money** testing - when they ALREADY KNOW what works for sure. They have **no fiscal motive** to test 100 combinations of synthetics and additives. But, I think you can bet that if something was causing enough problems to really care about - they would issue a real live warning - loud and fast.

I plan to put a call in to Eaton this week to try to pin them down as to *what* testing they have (or have not) done re synthetics. I'll follow up.

Yes - I agree with you that it would **very** helpful for a few people here to do the torque tests and see what different oil combos arrive at. I agree with you that the facotry combo works for sure - but those guys that cured chatter by going to a synthetic and no additive are also glad they did so.

All I'm saying is that you're right about the factory oils - but don;t be such a negative alarmist about the synthetic stuff - we don't KNOW anything except for what we hear here - and that's all anecdotal.

-W

 

I guess that having owned my car for 26 years and continuously made improvements along the way to EVERYTHING from the type of alternator, brakes, exhaust, engine mods, too numerous suspension improvements, on and on, I feel and know that what worked 30-40 years ago is definitely NOT the best for certain things such as fluids today, regardless of what WAS and is recommended for a part that is 30-40 years old. Everyone knows that many parts and fuids are much better than what came on the car or the fluids in it 30 years ago. The two events that happened with my diff that convinced me that the conventional fluid with the additive was not optimal was the chattering that occurred at 30,000 miles 20 years ago even though it was the factory fluid and the fact that Mobil 1 (without the additive) fluid 20 years hence has never produced a chatter or strange sounds from the diff. As for the correct amount of slippage from the Limited Diff checking with a torque wrench, I highly doubt most of the owners out there need to do that check to know if the Posi is working correctly. Does my diff leave even tire tracks when spun, yes? Does either wheel transfer power to the non slipping wheel on a wet/slippery surface, yes? Does it chatter with Mobil 1, no? Does it feel abnormally warm after extended highway driving,no? Is it quiet, yes? Has it lasted 20+ years with a synthetic gear oil with zero problems, yes? is there data to support synthetics in place of the conventional oil, yes? So using a combination of data, logic, real world experience operating with a synthetic, and 20+ years using Mobil 1, I feel pretty confident that the term chemist is probably not really applicable. Oh, by the way, speaking of chemist, a long term college buddy of mine who was a chemistry major at college and then went on to graduate school at the University of Chicago (one of the best) getting a PHD in CHEMISTRY has told me that using a synthetic in my diff is a very good idea especially when compared to conventional oil-now he IS a Doctor of Chemistry!

 

So far, this is more hard data than Eaton has provided us.

However, it does not help answer your serious question from the previous page - and that was a most worthy question.

-W

 

My last response was really to address the nay sayers about not using synthetic since the boys from Eaton don't "seem" to endorse its use but neither state that you should not use a synthetic, on the other hand-they are very coy with their recommendations as you have stated previously.

 

Question: What kind of oil should I use? Can I use synthetics? Do I need a friction additive/modifier?

Answer: Eaton Posi units perform best when using GL4 (or better) mineral/petroleum based gear oil. A four ounce bottle of friction additive/modifier is also necessary for optimum performance.

So the above from Eaton is somehow ambiguous? "Can I use synthetics?", "Performs best" and "optimum performance" is confusing to a few?

Is this also ambiguous from Auburn?:

"The Auburn Gear limited-slip differential design has been extensively tested with high quality non-synthetic 80w-90 hypoid oils treated with GM or Ford additive. To avoid differential clutch chatter and for optimum performance (limited slip effectiveness) use the oil and additive described above."

How about this from Dana/Spicer (for newer Vettes, for which mineral-based lubes are also recommended):

"Limited Slip differentials impose additional requirements on lubricants which cannot be covered by above specifcations (for GL-5, 80w-90). Some otherwise good lubricants do not preclude chatter or bumping in turning corners with Limited Slip Differentials. Many vehicles find it necessary to specify a special lubricant or a special additive for use with Limited Slip Differentials. Check the vehicle manufacturer's lubricant recommendations"

At some point, these three separate teams of engineers decided, independently, synthetics are a bad idea in this application. Why else would they go out their way to recommend against their use?

As far as this arguement from JB;

"I feel and know that what worked 30-40 years ago is definitely NOT the best for certain things such as fluids today",

...all I can say is, if you purchased a brand new Eaton Limited Slip carrier today, in 2009, it would come with a green tag attached that warns, in big letters, to use 'Use GL-4 or better Mineral/Petroleum Gear Lube and the GM Friction modifier'.

I agree synthetics have advantages in many applications; better mileage, runs cooler, longer drain intervals, higher heat tolerances, etc. And if the engineers believed their use would do all that, AND reduce warranty claims, they wouldn't hesitate to recommend their use in this application. But they don't.

Clams, you keep bringing up 'anectdotal evidence' as a reason to use synthetics. Do you really believe EA competes with the trillions of trouble-free miles on the millions of Eaton LS carriers using mineral-based lubes with the additive? Why would you believe EA instead of the engineers? Do you not trust the R&D?

Lastly, the Eaton posi carrier should have 60-75 ft/lbs of "slippage". You test by putting a puller-like tool on three of the wheel studs (after removing the rear wheel) and with the other wheel on the ground you apply the torque wrench. Less than 60 indicates clutch wear, mechanical problems, or incorrect gear oil. More than 75 indicates a need for more GM modifier, mechanical problems, or incorrect gear oil.

 

Actually... the above makes my point. I've contended all along that Eaton and Auburn units have millions of miles of "consumer testing" done with the factory lubes. I've further countered that no one is bothering to test the new synthetic lubes - because they don't have to. They have a legacy to stand on already.

You're the one that's contending that "because they bend over backwards to recommend the SOP factory lubes, that they have actually tested synthetics and found them somehow lacking". I've yet to see you post any indictment - or even evidence that they tested anything at all. You say they tested them - prove it.
I contend thay have not tested $hit - they don't have to. And they have absolutely no motive to go outside the hands that feed to look for trouble.

I *always* recommend Pennzoil Synthetic Blend (@50/1) for all post WW2 Mercury outboards with carb induction. Why? Becasue I've been testing it for years and years (as have all my customers) it's ashless and reduces "coking" around the rings. It's half the price of the Mercury Quicksilver stuff and does at least as good, and IMHO a better job. Mercury oil is made by the *lowest bidder* to specs cooked up off site by consultants. Guess what Mercury recommends? (hint - it's not Pennzoil)

Eaton has sold HOW MANY posi's in bed with GM? OF COURSE thay are going to recommend sticking to the "house lube" - it works very well and it comes from the hand that feeds - no reason to look closer. No reason to ever test competing lubes, etc etc... Follow the money.

-W

PS: Wal-Mart is now making *Redbox* paint all thier kiosks in remodeled Wal-Mart stores BLUE. See if you can tell me how this applies...

 

We don't know what's behind the recommendation to not use synthetics. R&D methods and results are proprietary. All we know is, three independent teams of engineers from Eaton, Auburn, and Dana/Spicer, have all concluded that synthetics are a bad idea in this application. That's all I need to know.

Clams, you say none of these engineers tested synthetics. Then I'll ask you, why do the engineers go out their way to tell us to not use synthetic lubes? Secondly, what information do you possess, that shows synthetics were not tested during R&D?

Lastly, I've provided documentation (service and maintenance manuals, and links from web-pages) from engineers that support the position that advise against synthetics.

Your turn. Go to the world wide web and find a credible recommendation that says synthetics are prefferred over mineral / petroleum gear oil in this application. And again, marketing materials from the sellers of synthetics won't pass the "credible" test. Any takers?

 

You keep telling me what they "say" - but I'm not seeing it in print. I'm not seeing any engineers, and I'm not seeing any reccomendations to not use anything. I'm seeing the lack of a positive reccomendation, and that's to be expected. Lets confine this to EATON before you drag in everyone on the web that makes or even smells a rear end.

Show me **exactly**where Eaton (who makes our posi units) says that synthetics are "a bad idea". (for that matter show me anything they say that is **proactively** negative.)

Like I said before, you are putting some words in thier mouth to fit your case. The other poster nailed it when he said they are being "cagey" regarding synthetics. They are indeed being very cagy - why?

-W

 

You guys are sure wasting a lot of your life BS'ing about posi & gear oil. The simple fact is, use the GM additive and either 90 or 85-140 gear oil and you're done. If you still have issues with a diff there is NO oil that is going to change it.
Posi hammer is caused by the spider backlash setting and the springs used to constantly load them. Some may never hammer, others may quiet down with the above oil change, and still others need attention from improper setup,wear, or abuse. There really isn't anymore to say but go at it seems like you're having fun.

 

Exactly what is "Cagey" or ambiguous about this recommendation from Eaton?:

Question: What kind of oil should I use? Can I use synthetics? Do I need a friction additive/modifier?

Answer: Eaton Posi units perform best when using GL4 (or better) mineral/petroleum based gear oil. A four ounce bottle of friction additive/modifier is also necessary for optimum performance.

 

You know what - I agree with you 100!

What I'm doing here to poor old Mr.Blue, is attemting to stop *disinformation* via his distorted spinning of the factory reccomendations. (or lack thereof).

We just don't know anything about the sysnthetics, if he'd leave it there he'd be fine. But he seems to have some imaginary engineer friends that are saying horrible, terrible things about synthetics - and I for one would like to see them quoted up front.

-W (welcome ot the no-spin zone)

 

What cagey is that they TOTALLY ducked the "can I use synthetics?" part of the questions. They instead went right into "safespeak" by answering question #1 and #3 and purposefully left #2 dangling in the wind with no answer. I think you need to do a stint in marketing (or politics) to smell a "duck and switch" - but that answer is a classic case of it. My point is - that you can read nothing negative about synthetics into that answer. They ducked the 2nd question on purpose - you can't see that?? Really?

-W

 

It's disinformation that I'm countering. I often see someone post a question that asks "what lube should I use with my Eaton carrier" followed by a couple of respondents that say to use synthetics.

This particular string asks "should the additive be added to a synthetic gear oil" followed by conflicting answers from self-appointed chemical engineers.

I'm simply stating, with supporting documention, that the advice to use synthetics, disagrees with the engineers who design these LS carriers; whether it's Eaton, Auburn, or Dana/Spicer.

Pour whatever you want into your differential, but it's clear there are risks with the use of synthetics, otherwise, why would the manufacturers go through the trouble to advise against their use? Why would they wire a green tag to every brand new posi sold that says to "use mineral-based 80w-90 lube plus the GM additive"? It doesn't say use any GL-4 gear oil or use either synthetic or mineral/petroleum oil; its says to use mineral/petroleum.

Like I said, if you run a synthetic, one of three things will happen;

1) It will run great
2) It will bump and chatter
3) Limited-slip (positraction) effectiveness will be reduced

If you run the recommended mineral/petroleum gear lube and additive, one of one thing will happen;

1) It will run great

 

Absolutely correct, but you're arguing with somebody that has an 'agenda'. I used to run into guys like this during my working career and had to listen to them because it was part of my job.

I'm really really glad I'm retired.

 

I AGREE with you that the factory oil is the best safe bet. It's your blatent distortion of the FAQ's that I object to. You are resorting to the age old debate tactic where you attemt to carry a point by "finding some experts" and then "using thier lack of a comment to make your stand". Plus, despite the fact that we are only concerned with Eaton posi units - you need to resort to a mix and match of 3 companies FAQ's in an attempt to try to cobble a cohesive point together at all.

In order to make your point solid you need to:

A: Actually produce some engineers (experts)
B: Actually pin them down to a stated opinion on synthetics - something the FAQ totally sidesteps. (engineers don't do the two-step that well - pnly marketing does)

So even *IF* engineers were behind the FAQ (and I sincerely doubt that), then you're still left with the problem that the Eaton FAQ deliberately ducks expressing *any* opinion on synthetics - they instead steer the buyer back to the approved factory oils and let the synthetic question hang on the vine. Which is exactly what I would do if I were writing the FAQ - ie. play it safe and avoid saying anyhting wrong at all. (if you don't say anything - you can't say anything wrong)

Synthetics are new... they are the future.... and I can assure you that the staus quo has no good reason to reccomend them or test them. I can also assure you that if they were causing real problems - they'd forbid them.

If synthetics are gonna get tested at all - it's up to us. It's up to small independent shops and race teams. It's up to anybody BUT Eaton to test them - they don't have to test anything at all so long as thier relationship with Detroit stays solid.

-W

 

Actually Mike - I don't have an agenda. Because I DON'T KNOW.
In fact I don't even know WTF is going into my own rear end yet - really truely.

My only "agenda" is to allow people who want to *try* some of the newer stuff (I'm not sure I'm one of them) be allowed to do so and report back here without being bullied about it - all because some FAQ is deliberately (and conspicuously) silent about synthetics.

When you read the Eaton FAQ, WITHOUT an agenda to put words in thier mouth to try to make a point - it's the blatent skipping over the synthetic question that screams out at you - not the other way around.

I maintain that the only "safe" way to go is the old factory combo, but I know also that the future is here - and the only ones that can try and report successes and failure is us. And I object to those people who "dare to be different" being labeled as "doing something wrong", all because of what an FAQ does *not* say. ie. If you've been using Mobil 1 for 10-20 years with outstanding results you need to be able to say so *here* without getting hit over the head with an FAQ twisted into a stick. If you switched to a synthetic and it was *worse* you also outta be able to say so without someone saying "I told you so".
I object when hard facts are replaced by "tactics" - and twisitng the FAQ's silence to fit an agenda is just "tactics". There are times when "I don't know" is the only right answer - this is surely one of them.

-W

PS. I just got mail in. DTE Powertrain Inc. (know who thy are?) reccomends Redline over Royal Purple by a large margin based on earlier tests. Thier current "overall" recomended lube is Redline as well.

 

Maybe that's why Kendall's additive doesn't work. They think it only needs to be an anti-foaming agent rather than a friction modifier.

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