Change gear oil in a 12 bolt

[BJCHEV396]

Hi guys,I've never changed the oil in the 12 bolt of my Camino.Would 2 quarts of 80w90 and a 4 oz.bottle of posi additive be enough?Thanks,Bill.

[bcmiller]

2 quarts is usually enough.

[big gear head]

Yes, unless you spill some.

[CamarosRus]

Big Gear Head............Could you list what options we have for POSI ADDITIVE ????

[big gear head]

The GM additive still works most of the time. The Ford additive seems to work better, if you don't mind putting Ford oil in your Chevy. Amsoil makes a good additive. I don't like the stuff that comes in a tube at the auto parts stores.

[SS427]

Yes, unless you spill some.

Don't spill it! You will have that unique smell in your shop/garage for weeks and it permeates everything!

I use only GM posi additive as I have had issues with anything else as far as clutch chatter.

[Too Many Projects]

Draining the old, used oil, is the strongest and worst, smell and there is no way to avoid getting that smell in a building, unless it is drained outside. The new oil, almost, smells good, compared to the old "stuff"...:wink:

[Salvatore]

I use the GM positraction axle gear lube in the old metal quart cans. I also use the limited slip differential fluid that comes in those small plastic containers. The old sperm whale fluid that is tuff to find these days.
I personally think it is better for the old original gears and posi plates.

[BARRY]

I use the GM positraction axle gear lube in the old metal quart cans. I also use the limited slip differential fluid that comes in those small plastic containers. The old sperm whale fluid that is tuff to find these days.
I personally think it is better for the old original gears and posi plates.

HI YES old school metal cans of oil the best

[Rsconv68]

IIRC, all 12 bolt rear axles were not automatically a posi traction.

[396 SS/RS]

IIRC, all 12 bolt rear axles were not automatically a posi traction. That is correct.

[big gear head]

Draining the old, used oil, is the strongest and worst, smell and there is no way to avoid getting that smell in a building, unless it is drained outside. The new oil, almost, smells good, compared to the old "stuff"...:wink:

When I had my rear end shop I smelled like that every day for 15 years.

[BJCHEV396]

Hi guys,I've never changed the oil in the 12 bolt of my Camino.Would 2 quarts of 80w90 and a 4 oz.bottle of posi additive be enough?Thanks,Bill.

And to seal it up...use just a quality gasket with or without silicone?

[Too Many Projects]

And to seal it up...use just a quality gasket with or without silicone?
I don't use silicone with a gasket...just lets the gasket slip out of place as you tighten the bolts.
And, yes, a good gasket alone.
Both surfaces white towel clean with acetone and dry.

[big gear head]

I put a film of RTV on both sides of the gasket. You will hear 20 different ways of doing it. Some people have completely quit using gaskets, but that didn't work out too well for me.

[Too Many Projects]

I put a film of RTV on both sides of the gasket. You will hear 20 different ways of doing it. Some people have completely quit using gaskets, but that didn't work out too well for me.
THAT is the key, a barely visible film, but too many people gob it on and create leaks.
When I use RTV, the only one I use is Ultra Black gasket maker, and Freddie's extensive experience is right, applied correctly, it is helpful. Next step for me, is, it needs to "cure" for 24 hours before I will introduce any fluids too.

[Zman1969]

THAT is the key, a barely visible film, but too many people gob it on and create leaks.
When I use RTV, the only one I use is Ultra Black gasket maker, and Freddie's extensive experience is right, applied correctly, it is helpful. Next step for me, is, it needs to "cure" for 24 hours before I will introduce any fluids too.

YES!
it needs to "cure" for 24 hours before I will introduce any fluids too

[SS427]

I have more often than not had leaks in my 12 bolt cover, with or without gasket, with or without black RTV. That is until I started using Permatex's 81182 Gear Oil gasket maker. I still use the gasket but put a thin layer of this on both sides and have not had a leak since. Like others have stated, give it overnight to set and you will have no issues.

[Too Many Projects]

I have never seen that product, Rick... :shocked:
I'll be getting a tube of that to have on hand.
Thanks !

[BJCHEV396]

Thanks for all the tips and info!

[1967 4K]

My experience with Permatex products is they do well when used for its intended purpose. Good stuff. I haven’t used this one before.

[69 Post Sedan]

I had a guy rebuild my 12 bolt. He’s been doing it for a LONG time…..Bob Kelso in Hebron IL. He only put grease on both sides of the gasket. He was adamant about ONLY using grease. That was 5 years ago and I’ve had zero issues with it leaking!

On a side note, I’ve rebuilt fire pumps for work. We would split the case, repack the pump and use silicone plus a gasket to seal it up. One time I worked with a company that specializes in repairing pumps…he also said to only use grease for the gasket…..and it works great plus a lot easier to remove at a later date if neede as silicone can be a PITA to remove.

Kurt :beers: