I know this horse has been kicked around alot.I am about to change my rearend oil in my 68.I've read the do's & don'ts on this forum; so I called up "Randy's Ring & Pinion" (where I got my "Eaton" posi)to see what they recommened.They said that snythetics were too slippery on the clutches and would turn a posi into an open differential.Just some info if anyone cared.

kool just to set the record straight,,,thats BS...
the Eaton folks make great gears, I have a new posi unit in my camaro now thanks to Big Gear Head. I also use Amsoil synthetic gear lube series 2000 in it with excellent results.
In fact the use is warrented by Amsoil itself if Eaton would renig on its mechanical conditon warranty, IF the oil had anything to do with it.
The folks at Eaton are old school when it comes to lubes, but they make great gears.
Read this and use it. you will love it since it runs cooler and does NOT hurt the posi unit.
This is a WORD document, you need MS WORD to read it.


Amsoil is fully warranted in Eaton Posi. Word Doc (http://www.brainerd.net/~knudsen/69RS/Eaton%20LSD.doc)

I better get a scrub brush and go remove one of the black marks out in front of my house. :eek:

I went with Mobil 1 synthetic after consulting the forums here. I trust the guys who are wanting to keep their cars on the road more than the guy trying to stay in business.

Just my 2 cents... or 3 cents if I can raise the price like the gas stations. :D

Amsoil 75W90 Series 2000. I use it in all of the Eaton posi rear ends that I build.

Click- I read the Amsoil warrenty. That's pretty cool when they'll warrent a product made by someone else(Eaton), especially when that product is in my car.Time to get some synthetic.Thanks for the replies guys.

Keep in mind kool, if the unit fails from mechanical problem such as installed wrong, measurements not set exactly right etc, the oil will test out as being not the cause of a failure, so Eaton still has to stand behind their product, mechanically. Installation is of utmost importance on a posi. ask Big Gear Head about very small tollerances.
The Amsoil warranty is to assure you that their products will not fail you.
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