one more rear end question.........

[LS1nut]

ok, my moser 12 bolt with HD eaton ,33 spline axles just went from having a 3:73 in it, to a 4:11.

before, I had royal purple syn fluid.

the mechanic put in Amsoil syn fluid.

before, with the 3:73 it didnt chatter at all (simple whining gear noise was the reason for the change to the 4:11)

well, with this Amsoil the damn thing is acting crazy when you try to turn a corner. should there be a limited slip additive added in with the Amsoil?

the royal purple didnt have an additive and I never had this problem.

thanks

[BeachZ]

I'm pretty sure the Royal Purple already has the additive in it. You would need to put in the additive for the Amsol fluid.

[jmd]

I agree with your initial thoughts. Sounds like your clutches need some friction modifier added.

[CT Morgan]

Yep... stick with Moser's suggested fluids... non-synthetic gear oil and friction modifier (use GM's).

[DrEvyl]

Yeah, if you're running an Eaton in there you need to use non-synthetic. Eaton specifically says that you should NOT use synthetic fluid with their performance carriers.

[LS1nut]

that sucks, cause Ive got the syn amsoil in there now.

damnit.

i gotta take it out and runt conventional and modifier.

:mad:

well, the good news is it stopped after the modifier was added to the synthetic fluid, but now i gotta flush that money down the drain.

weight suggestions?

[DrEvyl]

I'm running Kendall 80W-140 in mine.

[2REDGMC]

Originally posted by DrEvyl
Yeah, if you're running an Eaton in there you need to use non-synthetic. Eaton specifically says that you should NOT use synthetic fluid with their performance carriers.

I have asked Eaton about this statement.

After being given the run around I got the answer to why they make this statement.

Eaton has NEVER tested synthetic lubricants with their performance carries.

Why you ask. They don't see a need to test synthetic gear oils when they are not having any problems with the mineral oils.

Keeping in mind that the main difference between mineral oils and synthetic oils is the base oil, not the additives. The additives do the work and the base oil is the carrier for the additives. So if the additives are the same there should be no reason you could not use a synthetic oil with an Eaton carrier.

[DrEvyl]

Eaton strongly recommends utilizing an API-GL5 approved Mineral-Based 80W-90 Axle Lubricant and one 4-oz bottle of Limited Slip Additive (GM or Ford).

That's from their website.. The documentation that came with my Eaton said specifically to use a mineral based gear-oil rather than synthetic. I don't know why they say that, I was simply saying that they do.

I'm sure I could use a synthetic lubricant and it would work... I am simply thinking more that I don't want to give them any reason to deny a warranty claim should I have problems with it.

[LS1nut]

Originally posted by DrEvyl
That's from their website.. The documentation that came with my Eaton said specifically to use a mineral based gear-oil rather than synthetic. I don't know why they say that, I was simply saying that they do.

I'm sure I could use a synthetic lubricant and it would work... I am simply thinking more that I don't want to give them any reason to deny a warranty claim should I have problems with it.


well, I had a buddy of mine call moser directly, and they confirmed what you are saying Evyl.....however , since I dont have a warranty anyway (bought it used) I think im gonna leave the Royal Purple in it for a while.

the chattering has stopped and everything seems to be good.

if I have any problems I will post the results so people will know for sure from here on out.

if the Eatons stops working, im just gonna go to a spool and be done with it.

[CT Morgan]

Hmm... why would you want to risk burning up a $400+ posi just to keep the synthetic in the rear? Doesn't make too much sense.

I don't know the reasons why Eaton and Moser specifically say use non-synthetic fluids, but it is what they say and their products work wonderfully with those lubes. Easy decision for me. :thumbup: