posi rear differential gear oil recommendations

So it looks like I have a small rear differential leak around the pinion seal. Just a small spot after I rolled it out of the car bubble. Need to run it some and see what happens. If it ever stops raining. Any repair and/or gear oil recommendations appreciated.
71 GSX posi.

Thanks Zach

 

I’m running Amsoil & GM posi additive in my newly rebuilt rear end.

 

Anything at NAPA?

 

Which posi unit do you have?

 

Original, not sure.

 

Here’s what I use.

 

Question here. How long did Buick make the cone style differentials?

Start date:
End date:

Has Buick ever made a clutch disc differential for Buicks?
Especially for 70 thur 72 Skylarks?

 

You need to talk to Brian Trick. Brian is the guru on this subject. He just rebuilt a 70 - 8.2 cone style posi unit for me. He also sells new ones that he builds himself which work in the 8.2 Buick posi rear end but are Eaton style helical gear units (no clutches or cones). I bought one of those too to keep as a backup for my other 70’s.

 

https://v8buick.com/index.php?threads/gear-oil-recommendations.393350/

 

Mr. Brian Trick, can you answer the questions I've posted.
Appreciate your knowledge on this subject. Vet (Navy)

 

Any major brand of correct viscosity
. The addition of the GM posi additive is most important. Remember original posi oil was whale oil. No kidding. And boy did it stink.

 

I’ve read that some of the people who make new parts say NOT to run the synthetic stuff…
Patrick

 

Whale oil, that's interesting. When I started working in the Tool & Die trade, we used whale oil to quench the tool steel as we removed it from the oven to the quench bath to harden the steel.

It was found using whale oil did a much better job of quenching the tool steel in the hardening process.
Early on, in the hardening process of tool steel, water was used in the quench process. It was found water developed bubbles (like boiling water) on the surface of the tool steel, and this made for a poor incomplete hardening process. Now you know the rest of the story. lol Vet

 

That info is at least 20 years old… that card came with the Eaton LSD I have.
In all this time, I’ve yet to come across a reason why <shrug>

 

Thanks everyone for the information.
Zach

 

To the best of my knowledge:
the cone style posi unit was used in the BOP 8.2 through 1970,
in 1971 GM switched to the 8.5 corporate posi unit that uses clutches,
the 10 and 12 bolt chevy units with the eyebrow rib at the top of the cover uses clutches.

 

I my experience if doing any racing using the additive with cone type or clutch type just make it more likely to slip and be a one legger. I use regular non-posi gear oil. 85-w-90

The additive does make it smoother on the street and fine for street burnouts but at the track where there is more grip it can make it slip...too much.

 

Does anyone use the Lakewood BFL gear lube? I used to run that in my drag car and seen it recommended a lot.

 

Here is a pic of my 1970 GS Skylark 455 differential. It has a clutch disc in it and a 2.93 Posi.
I know this was added, I just didn't know you could install a clutch disc into a BOP 8.2.