Rear differential fluid amount
Thread Starter
Advanced
Joined: Mar 2011
Posts: 78
Likes: 1
From: SoCal California
Rear differential fluid amount
I'm in the process of restoring my 1969 Corvette L-71. Right now I have the whole rearend assembly out of the car as I am cleaning/painting it, adding new bushings/rear spring/shocks, installing new u-joints, and such.
While the rearend is out I will pull off the back cover to remove all of the old diff lube, verify the condition of the gears, clean everything out, add a new gasket and such. The question is ... how much lube does GM recommend for the rearend?
While I know that most guys fill the rearend until the lube just starts to run out of the fill hole ... I'm looking for the exact measurement that GM recommends.
And yes, I will add the proper GM posi lube when doing the re-fill.
While the rearend is out I will pull off the back cover to remove all of the old diff lube, verify the condition of the gears, clean everything out, add a new gasket and such. The question is ... how much lube does GM recommend for the rearend?
While I know that most guys fill the rearend until the lube just starts to run out of the fill hole ... I'm looking for the exact measurement that GM recommends.
And yes, I will add the proper GM posi lube when doing the re-fill.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
The differential will take about 1-1/2 bottles of diffy lube and a small bottle of Posi-trac treatment. GM did not specifiy how much lube it was to hold....just to stop when lube started to run out the fill port.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
http://books.google.com/books?id=lX5...amount&f=false
According to this book, on page 48, it says that '69-'76 diffs take 4 pints. I don't know why they couldn't just say 2 quarts. Anyway, the way a diff operates, I think it's more important for the fluid to be at the correct level, as opposed to a certain amount. Buy 2 quarts of fluid, the posi additive, and just top it off, you'll be fine, just fine. Good luck with your project.
Have you given any thought to adding a drain bolt while you have it apart? It would make future fluid changes much easier.
Keep the shiny side up!
Scott
According to this book, on page 48, it says that '69-'76 diffs take 4 pints. I don't know why they couldn't just say 2 quarts. Anyway, the way a diff operates, I think it's more important for the fluid to be at the correct level, as opposed to a certain amount. Buy 2 quarts of fluid, the posi additive, and just top it off, you'll be fine, just fine. Good luck with your project.
Have you given any thought to adding a drain bolt while you have it apart? It would make future fluid changes much easier.
Keep the shiny side up!
Scott
Last edited by scottyp99; Sep 4, 2012 at 11:23 AM.
Instructor
Joined: Jul 2008
Posts: 105
Likes: 1
From: germantown tn
well i just drained and refilled mine last week, first job on my new lift in the garage, car was pretty much perfect level. i sucked all the old oil out with a good pump and it was 100% full when i started, i am pretty sure it didnt leave much in there , you only use 1 bottle of the posi additive not two. ok one bottle of that and 2 gm differential lube which i think were like 23 oz each and it didnt fill up all the way i added just a hair extra to get to the top , of yeah 72
Safety Car
Joined: Oct 2004
Posts: 3,922
Likes: 733
From: Youngstown Ohio
well i just drained and refilled mine last week, first job on my new lift in the garage, car was pretty much perfect level. i sucked all the old oil out with a good pump and it was 100% full when i started, i am pretty sure it didnt leave much in there , you only use 1 bottle of the posi additive not two. ok one bottle of that and 2 gm differential lube which i think were like 23 oz each and it didnt fill up all the way i added just a hair extra to get to the top , of yeah 72
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