Change Rear End Oil HELP!!!!!
Thread Starter
Pro
Joined: Feb 2007
Posts: 548
Likes: 1
From: Victoria VA
Change Rear End Oil HELP!!!!!
I need to changen the rear end oil, it say do this between 36000 & 50000 miles. I have the new GM posi additive now what is the best oil to use? Is GM the best? Let me know what you all think.
Thanks
Thanks
Racer
Joined: Sep 2005
Posts: 453
Likes: 1
From: Austin TX
I used mobil 1 synthetic but I also put the posi lube in too. I used the generic auto parts brand "lubrimatic". I also use this brand of oil for the lower units of my boats and it works perfectly fine. I dunno if you're supposed to run it with synthetic or not, but I figured it wouldn't hurt.
I asked the people that built my diff if I should run the posi additive with mobil 1 and they said there's no need. Being as though my I had to remove my differential and have it resealed approximately 4 times by this company, I chose to run the additive because I don't trust them. My differential is still leaking btw...jeeez.
I asked the people that built my diff if I should run the posi additive with mobil 1 and they said there's no need. Being as though my I had to remove my differential and have it resealed approximately 4 times by this company, I chose to run the additive because I don't trust them. My differential is still leaking btw...jeeez.
Drifting
Joined: May 2005
Posts: 1,909
Likes: 6
From: Lake Arrowhead - Georgia > 72 Base Coupe & 74 BB Roadster
My "clutches" were chattering and would even make a grinding sound sometimes. Felt like a bad u joint. I used 90W Mobil synthetic and 2 bottles of the GM additive. Now it's SMOOTH!
Tech Contributor
Joined: Aug 1999
Posts: 15,193
Likes: 4,018
From: Connecticut, USA
I use either 90 wt or 80-145 Lucas gear oil and 1 bottle of additive in the diff's I build. I was advised against any sythetic gear oils from both Tom Watt and a US Gear engineer years ago. I paid heed to their advice.
If your diff is leaking they did not address a couple of common areas. It can be fixed but you may have to drop it out. Where is it leaking:
Pinion seal, yoke seals, vent, cover? How is the rest of the rebuild?
If your diff is leaking they did not address a couple of common areas. It can be fixed but you may have to drop it out. Where is it leaking:
Pinion seal, yoke seals, vent, cover? How is the rest of the rebuild?
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Burning Brakes
Joined: Jun 2004
Posts: 872
Likes: 3
From: Cortlandt Manor New York
The GM additive is the best and you already have it, so why not use it with the GM oil it was designed to be used with? As long as you can get it why screw around with other combo's?
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Thread Starter
Pro
Joined: Feb 2007
Posts: 548
Likes: 1
From: Victoria VA
Got My Fluid
I went to the Chevy dealership today after work. They told me I needed 3 bottles. I told them I only needed 2 qts. They said yea that’s right. 3 bottles they are only 23oz each. $24.00 total. I already had the additive. So I'll do the job after work tomorrow. Thanks for all your in put! 
Thread Starter
Pro
Joined: Feb 2007
Posts: 548
Likes: 1
From: Victoria VA
Did It ALL IS GOOD!!!
I spent most of the day working on the 77, one thing I did was go by Advanced Auto and got a hand pump and removed all the rear end fluid. Put the GM aditive and top it off with GM fluid. As soon as I started driving it I could tell a difference. Went to the parking lot and did about 10 circles right then left froward then back. And it is like new again. Drove the vette for about 1 hr and no chatter at ALL!!! I am HAPPY!!!!