How much oil in my 9 bolt rear axle?

Discussion in 'Got gears?' started by MartinNr5, Jul 25, 2017.

  1. MartinNr5

    MartinNr5 Stubborn Swede

    Hi all.

    Tried searching for this but the forum doesn't allow search words shorter than 4 characters. :rolleyes:

    How much oil do I need to put in my 9 bolt rear end for my 1972 Skylark (GS 455)? I've been searching on the net for the past 30 minutes without any luck. :mad:

    Thanks!
     
  2. PCUB

    PCUB PCUB

    Not sure on a 9 bolt but plenty of info on stock differential fluid change:
    http://www.v8buick.com/index.php?threads/differential-fluid-change.300615/page-2

    Typically you are filling to bottom of fill hole to where it just starts to overflow, run out. If you are looking for approx. amount, I would purchase 5 pints and you should have enough.
    Others may comment and get you closer to actual amount.

    Hope this helps!
     
  3. BrianTrick

    BrianTrick Brian Trick

    It's about 1.5 quarts. If you have a posi,put the additive in,then fill the rest with the gear oil.
     
  4. MartinNr5

    MartinNr5 Stubborn Swede

    Thanks for the replies, much appreciated!
     
  5. monzaz

    monzaz Jim

    well if your looking up 9 bolt rear..... that could be the reason your not getting the search results.
    10 bolt 1971 rear 8.5 - pretty sure 1.5 quart with additive will be a bit short. more like 2 quarts and additive.
    I think you use a lot of true trac units Brian which can result in less fluid as it takes up more cavity space.
    Pretty much the easiest fool proof way is to fill the cavity on a flat surface till the gear oil runs from the fill plug. THIS general rule of thumb will always carrier your differential with enough fluid to be safe.
    The cavity can vary from the type of unit you are using to the year casting that was made but if you have GM open or posi it will be roughly 2 quarts or 4 pints
    Never top off the fluid with the additive. that is very important as Brian said to fill with in the first quart and top off with gear oil. ALL the additive to be used. 4-8 oz depending on needs of posi unit and cavity capacity % ratio.
    So hope this clears some of the mystery.

    Look up 10 bolt 8.5 next time also. :)
    10 bolt stands for how many bolts are on the ring...which most of the time matches the cover bolt count....BUT NOT ALWAYS in GM ....

    Jim
    J D RAce
     
  6. MartinNr5

    MartinNr5 Stubborn Swede

    Yeah, I counted them, three times as I was sure that I had a 10-bolt. I could still be wrong, but at my age I should be able to count to 10. :) I'll be sure to double check the next time I'm in the garage. :D

    And for the record, I have an Eaton posi.

    Thanks for the help!
     
  7. monzaz

    monzaz Jim

    ok so an aftermarket eaton will take up a little more space than the traction lock GM unit....but still I am sure you sell the oil by the liter and or quart and you will need at least 2 to do the job.

    Jim
    J D
     
  8. MartinNr5

    MartinNr5 Stubborn Swede

    Got this done yesterday evening and I used up 4 fl oz of additive and 2 quarts of oil. I probably could've squeezed a bit more in there but that's all the fluids I had and it came really close to overflowing so I settled for that.

    And, I have to confess that at the age of 45 I can't count to ten. :D Not even when counting three times. :rolleyes: So, yeah, I do have a 10 bolt in reality as well, not just in theory. :)
     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I didn't even notice that at first, I thought you were talking about a Ford 9":D
     
  10. MartinNr5

    MartinNr5 Stubborn Swede

    Haha, no, I'll stick to "proper" parts. :D

    I also noticed earlier today that the seal wasn't tight so now I have quite a bit of oil dripping from the housing. :( Will go out and fix it now, hopefully without draining all of the fluids.
     

Share This Page