I CANNOT use synthetics in this application, so what are the top (cost NO factor) GL-5/6(?) 80W-90 (or whatever) petroleum gear oils out there?? So far I'm looking at; Lakewood BFL (yellow label), Torco RGO, Lucas 80W-90 (I know there are MANY Lucas haters on here, TELL ME WHY!!). Any other suggestions? Are these REALLY no better than the regular "off the shelf" Pennzoil/Havoline/Shell/Castrol/Valvoline, etc., etc., etc.??
Dino suggestions for Eaton Posi/GM 10 bolt
- Thread starter dailydriver
- Start date
- Status
MolaKule
Staff member
Are you sure the Eaton doesn't specify a special Diester-based synthetic fluid for this dify?
Please tell us why you dislike synthetics?
Please tell us why you dislike synthetics?
i know someone who put an eaton posi in their 9c1 and it came with a thing that specifically said no synthetic oil.
An Eaton retailer told me a while back that some synthetics adversly effect the friction characteristics of their carbon fiber clutch discs on the new Eaton Posis. Apparently the OE formulations are OK, but some of the aftermarket ones are too "slippery" and change the operational characteristics. I got the impression that they haven't tested all the oils out thre but there were a few that they know cause problems. I'm not taking all that to the bank and since I have a tech question on this from a reader in my files, I will ask my Eaton engineering contact and get back to you.
I was considering them also, but the specs did not seem too exceptional for the $$ and availability/hassle (sorry, Porschey boys, I know it's one of your faves
THANKS! I'd love to be able to use Redline/Amsoil SG/SF/ etc., but besides telling me it's too "slippery" (don't you love that high tech term?) and the diff will not work, they say that they definitely do an oil analysis on all returned for warranty diffs and DO NOT honor it if synthetics are found (can they really tell?). I'll tell you, if/when this thing goes out, I'm getting a Torsen T2R, then I can go around turns fast and use any synthetic I choose!
YOu must use mineral based gear oil in your Eaton Posi. When I bought my 31 spline eaton, it came with a little card with a warning. because fo the carbon fiber clutch plates, you cannot use synthetic oil. Don't know the chemistry behind it, but these posi units are virtually indestructable even in 10 second cars running on mineral based oil.
manufacturer's recommendation fluids are:
GM 1052271 (gM gear oil)
GM 1052358 (LS additive)
good luck.
manufacturer's recommendation fluids are:
GM 1052271 (gM gear oil)
GM 1052358 (LS additive)
good luck.
Has anyone used the Silkolene mineral based stuff? I was suprised to learn that they even bothered with a non-synthetic gear oil. I wonder how it compares to my other candidates?
I found this from Eatons info:
Heat, dirt and water are the worst enemies of any posi. Always replace the cover gasket and seal
it properly. A silicone sealant is recommended when using a non-synthetic gear lubricant; a non-
RTV sealant should be used with synthetic lubricants. Torque the cover plate and carrier bolts according to the manufacturer’s specifications.....
And from Randy RingPinion:
There are currently four different clutch plate designs available, three of which are worth considering. We will begin with GM's service pack which uses 18 all-steel clutches with cut-outs for oil. These clutches tend to chatter, and the cut-outs that are supposed to decrease chatter make the plates weak and prone to breakage....
So, is there really a problem with using synthetic??? I don't think so. I think that you need to make sure that you have the 'oil safe' sealant/gasket to prevent leaks. We all know what a leak leads to.....
And, as always with any posi, you need to have the correct amount of LSD additive. Chattering can cause failure in certain diffs.
Some gearoils, even when advertised as having LSD additive, don't have enough.
Heat, dirt and water are the worst enemies of any posi. Always replace the cover gasket and seal
it properly. A silicone sealant is recommended when using a non-synthetic gear lubricant; a non-
RTV sealant should be used with synthetic lubricants. Torque the cover plate and carrier bolts according to the manufacturer’s specifications.....
And from Randy RingPinion:
There are currently four different clutch plate designs available, three of which are worth considering. We will begin with GM's service pack which uses 18 all-steel clutches with cut-outs for oil. These clutches tend to chatter, and the cut-outs that are supposed to decrease chatter make the plates weak and prone to breakage....
So, is there really a problem with using synthetic??? I don't think so. I think that you need to make sure that you have the 'oil safe' sealant/gasket to prevent leaks. We all know what a leak leads to.....
And, as always with any posi, you need to have the correct amount of LSD additive. Chattering can cause failure in certain diffs.
Some gearoils, even when advertised as having LSD additive, don't have enough.
Are those comments/suggestions referring to the carbon fiber clutch packs, or only the steel clutch pack units?? Funny thing is, I've always been told that even the steel packs (as well as Auburn style "cone" units) must use a mineral based gear oil.
Doesn't a friction modifier take care of the "slipperiness" comments noted above?
I've got to add it to my Ford 9.75 LSD, but some gear lubes already include it.
I've got to add it to my Ford 9.75 LSD, but some gear lubes already include it.
The Eaton has the Carbon Fiber Clutch plates. Hence Eaton's requirment of a mineral based oil...
As for the RTV versus gasket debate...either one is okay for mineral/synthetic applications. you can always use RTV on the gasket prior to install of the cover.
As for the RTV versus gasket debate...either one is okay for mineral/synthetic applications. you can always use RTV on the gasket prior to install of the cover.
go with Chevron Delo Gear Lubricants ESI in their 80w90 formulated with Grp II ISOSYN technology and compounded with an extreme pressure, inorganic borate additive. They are well suited for gear sets exposed to extremely high temperatures and loads.
The diff will fail from hi temp hi torque shear loads before this lube fails. Many apps run 500k to million miles.
$million$ dollar industrial/commercial equipment relies on this lube
http://www.chevrontexacodelo.com/en/products/transmissionfluidgearoil/default.asp
[ March 22, 2006, 11:30 PM: Message edited by: Steelhead ]
The diff will fail from hi temp hi torque shear loads before this lube fails. Many apps run 500k to million miles.
$million$ dollar industrial/commercial equipment relies on this lube
http://www.chevrontexacodelo.com/en/products/transmissionfluidgearoil/default.asp
[ March 22, 2006, 11:30 PM: Message edited by: Steelhead ]
Any quality dino gear lube will work. Valvoline 80W90 is my personal choice. Just be sure to put a bottle or two of the GM friction modifier in or else you will destroy your clutch packs.
You can use RTV on the diff cover. Permatex Ultra Copper works the best and if you use it, use it sparingly. Just a thin smearing on the diff cover is all you need. Too much RTV will eventually break off and get into a bearing and destroy the rearend. I'm a mechanic and have seen it happen many times over the years, so go easy on the RTV. If you use a gasket, don't use RTV...use a gasket sealer/adhesive to hold the gasket to the diff cover to make installation easier. Edelbrock's Gaskasinch is the best sealer out there.
You can use RTV on the diff cover. Permatex Ultra Copper works the best and if you use it, use it sparingly. Just a thin smearing on the diff cover is all you need. Too much RTV will eventually break off and get into a bearing and destroy the rearend. I'm a mechanic and have seen it happen many times over the years, so go easy on the RTV. If you use a gasket, don't use RTV...use a gasket sealer/adhesive to hold the gasket to the diff cover to make installation easier. Edelbrock's Gaskasinch is the best sealer out there.
Dailydriver, I'm still working on this to get a definitive answer from experts and engineers, but Eaton has a direct oil recommendation, for the Posi:
1) Texaco 9622 mineral based 80W-90 with 4-oz of limited slip additive.
2)Aany mineral based 80W-90 GL-5 with the LS additive
I'll have more info soon that will be more comprehensive.
1) Texaco 9622 mineral based 80W-90 with 4-oz of limited slip additive.
2)Aany mineral based 80W-90 GL-5 with the LS additive
I'll have more info soon that will be more comprehensive.
Eaton Corp built the old Positraction under contract for GM, startging back in 1961 (Dana made the original "Posi" followed by Saginaw). Eaton best known for being an OE supplier of drivetrain parts and truck axles (till '97.. they sold that division to Dana). They also have an aftermarket division, which was greatly expanded when they recently bought Tractech (makers of the Detroit Locker, the Electrac, EZ ocker and Trutrac among other stuff). The aftermarket Eaton Posi was introduced in '99 and uses carbon fiber clutch discs rather than the traditional metal backed bonded discs (or metal discs). The carbon fiber discs are the source of the discussion here because it has been widely reported that certain synthetics will both cause functional difficulties with the Posi as well as deterioration of the carbon fiber disks. That has been confirmed by some pretty reliable industry sources (though not from Eaton yet). I have some contacts in the drivetrain industry and am following up on this to get a more definitive answer. So far, it looks like the factory fill syns amy be OK but it's the aftermarket "boutique" oils that may be the problem, i.e. the good stuff. Go figure. Your OE Eaton may not be (probably isn't, all the OEs I can find aren't) the carbon fiber unit, though if you could confirm that, it would add to the discussion here.
OK, here's the word from my source at Eaton: Use syn or dino, as long as it meets a GL-5 spec. There are no serious compatability issues using syn oils. To repeat, Eaton recommends specifically Texaco 9622 mineral based 80W-90 with 4-oz of limited slip additive but you are not restricted from using other oils, including synthetic.
The anecdotal thumbs-down comes mostly from drag racers, many of whom think syn oil is not the hot stuff for drag racing (claiming shear strength and shock load issues???). Not sure about where the compatability with the carbon fiber discs "common knowledge" came from, but it was repeated by a lot of sources I would call reliable. Normally. But I'd go with what eaton says over "common knowledge" I guess.
The anecdotal thumbs-down comes mostly from drag racers, many of whom think syn oil is not the hot stuff for drag racing (claiming shear strength and shock load issues???). Not sure about where the compatability with the carbon fiber discs "common knowledge" came from, but it was repeated by a lot of sources I would call reliable. Normally. But I'd go with what eaton says over "common knowledge" I guess.
- Status
Similar threads
- Locked
- Locked