Hi Mike,
I always use Valvoline 80W-90 Conventional Gear Oil. If you have a Posi, also add one bottle of GM Limited Slip Additive.

 

Me too. Sta-lube 80w90 GL4. I went with the Ford Racing CM-19546-A1 Friction modifier for the posi.

 

Valvoline 80w90 Durablend. It already has the friction modifier in it for posi.

 

Lucas oil 80w 90 add the gm limited slip additive if posi as mentioned :thumbsup:

 

I also use Sta-lube 80w90 GL4 and one bottle of GM Limited Slip Additive (additive only if it's a limited slip positraction differential).

 

Amsoil 80w-90, if its a posi, their gear lubes already have the posi additive in it. It worked great in my 12 bolt Eaton posi.

 

If you're running a posi (limited slip) carrier, Eaton (who makes the carrier) recommends against synthetics. Run the recommended conventional gear oil instead, 75w90 or 80w90, with the GM additive.

If she's not posi-traction, run most any quality gear oil.

 

And just some unsolicited advice (if you haven't done the oil change before): make sure you can get the fill plug out before you crack open the rear cover and drain all the old oil out!

I almost didn't check but when I did I found it was stuck pretty good. There wasn't a lot of room under there for leverage and I couldn't get it to budge, so I drove down to a local shop. They put it on a lift, cracked the plug open then closed again. Took it home and was able to get it out easy peasy. I wish I could say the same about getting that thick *** oil into the diff...

 

Worst case scenario (if you don't care about originality), they make aluminum diff covers with a fill and a drain hole in them.

 

Break down and buy one of these to refill your gear oil.

 

Where do you get this (and what specifically is it called?)? Good grief I wish I had something like that when I did mine! My hands and arms were aching from holding the bottle up and trying to squeeze that molasses/oil out. Seems like it took an hour just to do that part.

 

Those square head plugs can be a problem. There are several tool supply companies that make 8-point sockets. They are real handy for both the diff. and the Muncies. Cheers, Fred

 

...or you can replace it with a pipe plug that accepts a hex key.

 

In the pic, lower left, you can see the new hardware I used. I took the old plug to the hardware store and found one without the square head. Can't remember off the top of my head but it is a standard common size that I do have a socket for.

 

Just a tip guys, the local fast food auto mart as well as all marine dealers sell a gear lube hand pump for putting lower unit oil in outboard, sit it on top the container and it makes differential oil change a breeze,lot less mess as well.
Wallyworld has them around ten bucks.
I have the moser cover with the plug which makes it a breeze.

 

^^^...your reply is to a 5 year old thread....but yeah "hand pump" for fluids is the way to go to fill differential and manual transmissions.

I have one that is a 1 qt oil type bottle with a hand pump

 

can somone post a link of the one they use for these thicker oils? diff's and manual trans fill?

 

This is the one I have. You can use any empty oil bottle. IIRC it was hanging next to the Sta-Lube gear oils at the auto part store. Often gear oil comes in those bottles with the tip you cut off and squeeze. Just pour that oil in a empty oil qt plastic bottle

https://www.amazon.com/Sta-Lube-SL4344-Fluid-Oil-Pump/dp/B000CPIOBA

With a longer plastic hose you can also "pump out" from the tranny fill tube if you over fill or have to remove some fluid to pour in some type of additive if tranny pan does not have a drain plug

This pump works easily with thick gear oil or ATF that I use in my T56

 

Hi all,
I was trying to find what kind of oil for my 10 bolt camaro 68 differential and I have seen your answer about the additive for the posi…
Very sorry for my silly question but I dont know what a "posi" is and how I could check that I have one on my camaro ?
Thanks for your help and understanding about my beginner level !
I have a constant noise at the back of the car when I drive so I would like to change the oil first… do you see anything else I should do / check ?
Clement
NB : first ride with the car after a 4 years restoration so I dont know if the noise has been there for a long time or not

 

"Posi" is short for Positive Traction, which is the trade mark name for the Eaton clutch type limited slip differential. The name has been applied to all limited slip differentials over the years, much like Roller Blade has been applied to all brands of inline skates, and Kleenex to all brands of facial tissues. It's not correct, but that's just how it is. So the short answer is, Posi means limited slip differential.

Most LSDs require a special oil additive to help the clutches slip smoothly when turning corners. It reduces the clutch chatter and makes them operate more smoothly.

 

To determine posi or open differential: Raise the rear of the car so both tires are
off the ground. Put transmission in neutral. By hand rotate one of the rear wheels
and observe the direction of rotation of the opposite wheel. If the opposite wheel
is rotating in the same direction you have a posi differential. If the opposite wheel
rotates the opposite direction you have an open (non posi) differential.

 

That doesn't work on many "posi" rear ends because the clutches have lost their preload and will slip when turning one wheel. Also, sometimes a damaged rear end will cause both wheels to turn in the same direction when doing this. A bent axle tube, galded cross shaft and other things can cause this. The only way to tell is to remove the cover and take a look inside.

 

Or just use one of these. It will work fine either way.

https://www.valvoline.com/our-products/grease-gear-oil/high-performance-gear-oil

https://www.valvoline.com/our-products/grease-gear-oil/synpower-full-synthetic-gear-oil

 

Both Eaton & Auburn advise DO NOT use synthetic gear oil with their LS Diffs if OP has a LS aka "possi"

 

Hi,
The car is leaving tomorrow for the final paint job so I won't have time to open the differential but I will send you a picture when I will do it (not before a couple of weeks...)
Thanks again