What Rear End Fluid with Eaton Posi? [Archive] - Team Camaro Tech

: What Rear End Fluid with Eaton Posi?


Black Z
Dec 31st, 06, 09:45 PM
What brand and weight rear end fluid should I use with a new eaton posi in my 1969 camaro 10 bolt? Also what limited slip additive should I use? Thanks

Straight-line-69
Dec 31st, 06, 10:17 PM
Eaton "strongly recommends" conventional/mineral lubes plus the GM "limited slip" additive (GM part number 10522358) for use with their posi's. Valvoline 80-90w works for me.

Black Z
Dec 31st, 06, 11:50 PM
Eaton "strongly recommends" conventional/mineral lubes plus the GM "limited slip" additive (GM part number 10522358) for use with their posi's. Valvoline 80-90w works for me.

By conventional/mineral lubes does that mean no synthetic oil? What weight do they recommend, it does not say on their website?

click
Jan 1st, 07, 07:07 AM
Alot of us use Amsoil Synthetic Gear lube 75w90, it has the additive built into the oil itself. While Eaton shys away from recommending Syns, (they cant seem to find the time to test their units in all the variety of lubes out there), Amsoil does warrant their product in the Eaton gears. It will run MUCH cooler and give better mileage than a dino oil. Many rear end rebuilders highly recommend the Syns.

big gear head
Jan 1st, 07, 07:53 AM
I use Amsoil 75W90 Severe Gear synthetic oil in them. No problems in 10 years. GM has been using synthetic oil with Eaton differentials for around 8 years now. 2 quarts will usually fill it. Otherwise use 80W90 petroleum oil with GM or Ford additive.

Jonesy
Jan 1st, 07, 08:18 AM
I'm with Click and BGH. AMSOIL is what I put in mine without any problems also.

rogue68
Jan 1st, 07, 08:52 AM
I run the conventional + additive w/ Eaton and works great. Never even thought about synthetic. I wonder if there are any issues switching between the two?

Black Z
Jan 1st, 07, 09:12 AM
What about for the initial 500 mile breakin period? Would it be like an engine breakin period where it is recommended to use only conventional oil, no systhetics? Do all of the amsoil oils have the limited slip additive in it already?

ept000
Jan 1st, 07, 09:31 AM
I used Redline synthetic and it chattered like crazy. Changed to Valvoline and the GM additive and it's perfect now.

Black Z
Jan 1st, 07, 09:37 AM
I used Redline synthetic and it chattered like crazy. Changed to Valvoline and the GM additive and it's perfect now.

If it chattered you probably did not use an oil with limited slip additive?

big gear head
Jan 1st, 07, 09:43 AM
I have always used Amsoil from the beginning with no problems. Only the Severe Gear oil has the additive. This replaced the old Series 2000, which also had the additive.

Black Z
Jan 1st, 07, 09:55 AM
I am thinking of trying the Redline Synthetic 75-90W GL-5 with friction modifier? Would that be a good choice?

Hogdaddy
Jan 1st, 07, 11:21 AM
Eaton "strongly recommends" conventional/mineral lubes plus the GM "limited slip" additive (GM part number 10522358) for use with their posi's. Valvoline 80-90w works for me.

I just put a new 8.5 Eaton posi in and the instructions said mineral lube only and no where did it say its ok uses synthetic so have they not upgraded the instructions included with these posi's?

ept000
Jan 1st, 07, 12:11 PM
If it chattered you probably did not use an oil with limited slip additive?
No, the bottle said "for limited slip differentials" right on it. The chattering stopped the day I switched to Valvoline. Redline probably makes great products, but the Eaton posi defintely does not like it. I called Eaton a while back and asked why they don't recomend the synthetic oil and they said it was "too slippery" and it caused thier unit to chatter. I know lots of you guys and gals are using Amsoil, and like it. I will stick with Valvoline because it works, and it's not worth my time to "try" something else.

olympic69
Jan 1st, 07, 12:25 PM
No, the bottle said "for limited slip differentials" right on it. The chattering stopped the day I switched to Valvoline. Redline probably makes great products, but the Eaton posi defintely does not like it. I called Eaton a while back and asked why they don't recomend the synthetic oil and they said it was "too slippery" and it caused thier unit to chatter. I know lots of you guys and gals are using Amsoil, and like it. I will stick with Valvoline because it works, and it's not worth my time to "try" something else.

Thats kinda bizzare- I thought the chatter was the result of _innadequate_ lubricity/ film strength, and the clutch packs grabbing instead of slipping as they should, albeit under the high pressure of the pre-load springs and side gear forcing under load. That is why it is critical that limited slips use an extreme pressure (EP) lube or additive, otherwise the clutches will be damaged.

I think I would go with the consensus product(s) listed earlier in this thread- that being the Amsoil severe gear product which others have used with good result- in other words, you dont need to experiment!

Rob

Hogdaddy
Jan 1st, 07, 01:51 PM
Thats kinda bizzare- I thought the chatter was the result of _innadequate_ lubricity/ film strength, and the clutch packs grabbing instead of slipping as they should, albeit under the high pressure of the pre-load springs and side gear forcing under load. That is why it is critical that limited slips use an extreme pressure (EP) lube or additive, otherwise the clutches will be damaged.

I think I would go with the consensus product(s) listed earlier in this thread- that being the Amsoil severe gear product which others have used with good result- in other words, you dont need to experiment!

Rob

Experiment? Those Eaton's been doing fine for years with convetional oils and maybe synthetics are ok I dunno but some folks may be biased here.

mkpatrick
Jan 1st, 07, 02:00 PM
What do you all think of Royal Purple 75W90? I have a 12 bolt that I just changed the gasket on and was ready to add some gear oil.

I had some Slick 50 but no where on the bottle did it say anything about limited slip or posi so I didn't add it.

But I saw the Royal Purple and............

just wondering about any reviews from the crowd here.

Black Z
Jan 1st, 07, 02:04 PM
Thats kinda bizzare- I thought the chatter was the result of _innadequate_ lubricity/ film strength, and the clutch packs grabbing instead of slipping as they should, albeit under the high pressure of the pre-load springs and side gear forcing under load. That is why it is critical that limited slips use an extreme pressure (EP) lube or additive, otherwise the clutches will be damaged.
Rob

That is correct. This is from Redlines website:

LIMITED-SLIP COMPATIBILITY
Red Line Gear Oils, with the exception of the
75W90NS, and 75W140NS, already contain friction
modifier required for operation in limited-slip differentials.
Additional additive is not usually required, but
newer units or those with more lockup capability may
require 1-4% additional Red Line Limited-Slip Friction
Modifier. If Red Line is not available, the manufacturers
recommended friciton modifier is compatible. Do not
add addtional modifier unless necessary, as too much
will result in excessive wheel spin. To perfectly tune a
differential, start with the 75W90 NS or 75W140 NS and
add the Red Line Limited-Slip Friciton Modifier until the
limited-slip chattering just disappears.

olympic69
Jan 1st, 07, 02:35 PM
Experiment? Those Eaton's been doing fine for years with convetional oils and maybe synthetics are ok I dunno but some folks may be biased here.

Nothing wrong with the great EATON product IMO, I just would not want to go looking for different lubes when some have an established record for performance in a limited slip application. I dont have any bias, nor have had any problem with a conventional gear lube and the GM LS/ EP additive.

Cheers-

Rob

big gear head
Jan 1st, 07, 03:21 PM
The petroleum oil will work just fine with the GM or Ford additive. I just listed what I use. I'm not trying to push it, just saying that it works well and people shouldn't be affraid to use it. GM uses (starting in '98) synthetic oil with the clutch type Eaton in the trucks and it isn't causing any problems. They use the same carbon fiber lining on the clutches as the new Eaton posi. Amsoil Severe Gear is the only synthetic that I know of that works well without having to use any additional additive. Mobile 1, Red Line and others seem to need additional addtive to work well. There is nothiong wrong with using the petroleum oil. If that is what you like and feel safer with it then go with it.

Straight-line-69
Jan 1st, 07, 05:02 PM
As I've stated before, in another post, part of R&D that engineers engage in, is inspecting failed units. As posi's are returned for warranty purposes, etc, they're studied a part of quality control. I'm sure the "strong recommendation" to use conventional/mineral lubes is the result of a much higher ratio of failures using syns. So Eaton spends time and money making sure their posi's aren't used with syns.

Here's my post from this same discussion earlier this year:

"Don't know about the newer locker units with different clutch linings, but we're talking about two different technologies.

This is straight from the Eaton site,..the FAQ section regarding the Limited Slip defferentials:

"What type of lubricant and limited slip additive should I use with my newly purchased Eaton Limited Slip Differential?"

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)."

Here's the site:
http://www.traction.eaton.com/prod6.htm

More info:
http://www.traction.eaton.com/prod3.htm

And info about their lockers:
http://www.traction.eaton.com/prod2.htm

Here's another concern after some research on the Vette site,..a few over there have experienced reduced effectiveness of the Eaton posi with synthetics. The thinking is that the slippery synthetic can actually cause slippage.

Also, do you not agree Eaton (who's been around for 100 years) studies and logs the causes of failed posi units? Or do you believe Eaton simply tosses them aside and hopes the next one works?

Lastly,..since 1961 (Eaton's first posi), how many billions of trouble-free miles have been logged on how many million Eaton posi's that almost always out-lasted the cars they were used on, primarily with the use of petro gear oil?