Rear Differential Fluid Change.

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by stchman, Jun 10, 2013.

  1. stchman

    stchman Active Member 1 Year 1000 Posts

    Changed the fluid in the rear differential. The amount of fluid that I removed was ~2.25 quarts, and the fluid I put back in was ~3.25 quarts. I put fluid in until it ran out the fill plug. I wonder why the difference?

    Used Mobil 1 75W-90 gear oil.
     
  2. j cat

    j cat Rockstar 4 Years 1000 Posts

    the 10.5 takes 3.25QT / 9.5 2.7QT .. now on filling with the vehicle LEVEL in warm weather fill to just below the fill hole. in cold weather fill to 1/2in below the fill hole. this fluid when hot expands.

    since you drained out A QT less then you must have a leak. check the fluid every oil change for level and fluid color.
     
  3. steved

    steved Former Member


    Could be as simple as the position of the asymmetrical center section...turn it one way and it will displace more volume than if its turned 90*. Depending on its position when it was last filled...

    A leak on a differential should show up pretty readily. Even an ounce will make a complete mess underneath a truck; let alone a quart.
     
  4. j cat

    j cat Rockstar 4 Years 1000 Posts

    there is a vent tube hose if it got very the fluid may have come out of it as another possible cause or maybe it was never filled to the proper level this can occur if the vehicle was not on level surface.
     
  5. steved

    steved Former Member

    I want to say mine was "low" by my standards when I brought it home...it was around a 1/2 inch (or more) below the fill hole. I'm thinking they probably fill them by volume (automated, so to speak), and not by level...I fill this one to where the fluid runs out the fill hole.
     
  6. stchman

    stchman Active Member 1 Year 1000 Posts

    My truck has the 8.6" ring gear. I have your standard 10 bolt G80 locking diff. There are no leaks on the axles, pinion or other areas. The truck is a 2013

    After reading a BUNCH of posts on other forums I gather the capacity of that particular diff is ~2.5 quarts. Many have said that the proper fill level is 0.5" below the fill plug.

    I filled the diff up until it came running out of the fill plug and waited for it to stop running out. Is this improper, I don't know, I've always filled gearboxes up until the fluid came running out of the fill plug.
     
  7. steved

    steved Former Member

    I have a 10.5", and I want to remember the 10.5" is "level with the fill hole"; but I do know it depends on the differential.
     
  8. stchman

    stchman Active Member 1 Year 1000 Posts

    You must have a 2500 Silverado.

    I was under the impression that the 2500 and 3500 rear differentials were made by Dana while the 1500 diffs were made by Eaton.
     
  9. steved

    steved Former Member


    The only Dana I know that GM used in a rear application was the Dana 60 in some of the 3/4 ton vans a while back. Until they switched to IFS, they used the D44 (later replaced by the Corp 10-bolt) and D60 for the front axle.

    This 10.5 is what i know as a "Corporate 14-bolt", and its design has been in use by GM since the late 60s/early 70s.
     
  10. stchman

    stchman Active Member 1 Year 1000 Posts

    Before this thread gets too far off topic:

    I would like the opinion of some of the forum members as do they think that filling G80 8.6" differential on a 2013 SIlverado up to the fill plug is bad, good, does not matter?

    Thanks.
     

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