[Calebs67rs]

I just intallled a new Eaton posi unit in the 12 bolt in my 67, What is the best type grease to use with these? My father in law is a royal purple dealer and I can get some of their grease from him, but I am not sure about using synthetic in a rearend. Any help appreciated. I did a search on the subject but couldnt find much. Seems like I read on here once that the really slick oils like the synthetics defeat the purpose of a posi unit. Thanks for any replies. [img]graemlins/beers.gif[/img]

[BPOS]

I just put an Eaton in my 10 bolt. I was told that synthetic lube is too slippery and the posi won't work correctly. Use a good quality petroleum based lube of the weight recommended by Eaton (mine was 80W 90), and add a 4 oz. bottle of friction modifier, such as GM Posi-Lube, part #1052358. This will keep the posi from "chattering" as you go around corners.

[click]

Ok guys B.S. alert here. A good synthetic lube is your BEST bet for those Eaton posi's

Amsoils series 2000 gear lube already has the posi ingredient built into the lube and it works GREAT.
I just had an Eaton 3.08 posi installed last summer and its purring like a kitten.
A synthetic that is not built for posi might need the additive you speak of from GM.
The syns will not negatively affect the slip, so go ahead and use it. There are many others in here that also use the syns in their posi's with great results.
If you use the 'search' function again, type in the name Big Gear Head for user name and you will get a long list of threads dealing with lubes in Eatons.
He is a dealer for Eaton and also for Amsoil as I
am too.
Hope this clears things up.

[img]smile.gif[/img]

[BPOS]

Here is the scoop, straight from Eaton. This card was in the box with my posi unit.

"The Eaton Posi LSD you have purchased should be installed using a Mineral based gear oil 80 W 90 (GM#1052271). As an extra precaution for heavy usage applications it is also recommended to use 4 oz. of GM Limited Slip Axle Lubricant additive #1052358. The Eaton Posi LSD is NOT recommended to be used in synthetic oils because of the naturally higher temperatures created by the friction discs." (Emphasis not mine)

If you consider this to be "BS", then good for you... you must know more than the engineers who designed it. I have chosen to operate mine as recommended by the manufacturer.

[click]

I had the same tag in my Eaton box when it arrived and I promptly threw it out. The tech people at Amsoil have talked with Eaton about this and Eaton is concerned about some lesser quality syn's on the market that are not up to the challenge. Having heard this direct from Amsoil and the fact that their product warranty covers its use in Eatons, I have and will continue to recommend its use. Big Gear Head who sells and installs Eatons, (from this site) also uses Amsoil in his Eaton installs for years now as well.
Obviously, it would be in Eatons best interest to revise their little carton tag but until they do, folks have to do their research, talk to people knowledgable in the field of lubes and act accordingly.
I respect a persons fear of that tag and have offered the rationale that the lube 'engineering' experts have passed along.

The right products work great. [img]smile.gif[/img]

[BPOS]

[Obviously, it would be in Eatons best interest to revise their little carton tag but until they do, folks have to do their research, talk to people knowledgable in the field of lubes and act accordingly.]

Actually, I think it would be in Amsoil dealers' best interests for Eaton to revise their little carton tag.

What you say may be true...but until I hear it from Eaton, I'm stickin' with dinosaurs!

Cheers.

[click]

Its a catch 22 really. Amsoil says to use their product with the protection of their warranty to back it up. They asked Eaton to change the tag but Eaton says other products out there still wont do the job, so they want to opt out of their problem with those by using the tag. To exempt Amsoil or others from their tag would then endorse that oil over others and around and around it goes.
Ive used Amsoil since 1975 and never had a problem and as long as they back their product with warranty and make the recommendation to use it, a consumer is safe, either way.
But you do what you feel is right, no fault in that. I just know my posi will run over 20 degrees cooler and that translates to reduced friction and longer life.
Thanks for the word swaps [img]graemlins/beers.gif[/img]

[BPOS]

I'm NOT trying to start a fight or be nasty...honest. And I'll listen to and respect your answer...but I don't think "reduced friction" is necessarily what you want in a posi. There has to be a certain amount of friction for a posi to do what it is designed to do...to provide traction to both wheels in the straight ahead mode, yet slip enough while going around corners to provide differential. If you were after "reduced friction" you'd also put whimpy springs in them.

Amsoil might be just perfect for these things. And I certainly am not saying that it will cause harm. I just think that if you want the posi to grab tight when it should, more friction, not less is the answer.

[big gear head]

I always use Amsoil 75W90 Series 2000 in all of the posi rear ends that I build, unless the customer goes against my advice and uses something different. It has always worked without any additive, except for Auburn limited slip differentials, which don't work well with any kind of oil. You can take my advice which comes from 21l years of experience building rear ends and 6 years of experience with Amsoil, or you can use something different.

[RW68RSConv]

"Amsoil says to use their product with the protection of their warranty to back it up."

Does this mean if the posi fails (due to lube)- Amsoil will pay for the repairs/replacement?

I'm very curious as I will be ordering a new Eaton in the next 15 days. I always wondered because the first thing the magazines do is put in high quality syn and the brag about how great it is. My next door neighbor installed an auburn last month and went with old technology because he had a similar card in his box and was scared of warranty issues, much like Calebs67rs.

[click]

Yes thats right. A warranty is a warranty. If you have failure in mechanically sound application, after using according to their recommendations, with lab tests on the used product to confirm its condition, their warranty stands.
The reduced friction that comes from using the syns is primarily where the teeth meet not just the turning radius friction. Petro lubes loose out under high pressure and the teeth can meet for micro seconds where the metals touch. That is where the heat comes from as well as the sheer as the lubes are squeezed between metal.
Maybe Big Gear Head and I can make another ovature to Eaton to reconsider their box tag again. This issue keeps coming up and never ends.

[Calebs67rs]

Thanks a lot for the replies, I have decided to go ahead with the synthetic oil.

[BPOS]

Just as a follow-up - I called the shop where my ring and pinion was set up. He has been doing these for 30 years, mainly for off-road vehicles, and is not an Amsoil dealer. His reply - don't use synthetic.

BPOS out.

[big gear head]

The reason that most people are afraid of synthetic oil is because they heard about someone who knows someone who may have had a problem with something that was actually not even related to the oil, but the oil was the first thing that got blamed. People who are afraid of good synthetic oil listen too much to myths and not the facts. The fact is that no petrolium oil is as good as a good synthetic oil. There are some junk synthetic oils, but there are a few that are really good. I'm not trying to **** anyone off, but it does get frustrating when people fight what they don't understand. Ok, I'm done venting.

[BPOS]

Big Gear Head and Click: Please don't be frustrated or P.O.'d...that was never my intent. You have even mostly convinced me, a 45 year old skeptic, who is set in his ways, that Amsoil will work just fine with the Eaton posi. But please understand where I am coming from. The people who design and build these things recommend against synthetic lubes for them, and so far, the only people I have heard who recommend synthetic lube for them are you two, who sell and profit from its use.

I consider myself to be a reasonably savvy consumer. When I pay good money for a product, and they specifically recommend against using synthetic oil in it, I'm going to heed their advice. This doesn't mean you guys are wrong. But, skeptic that I am, I need to hear it from Eaton.

I guess what really torqued me off was the fact that my opinion, which is based on the best advice from the manufacturer, was considerd by one of you to be "BS". I would suggest that you give people a little credit as far as being able to read the directions before discrediting them.