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Rear Differential Fluid

HeySkippyDog

By HeySkippyDog
in Engines & Drivetrain

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HeySkippyDog Senior Enthusiast

HeySkippyDog

Posted
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Changed my rear differential fluid today at 52,000, first change on my 2017.

 

Metal shaving sludge was moderate, I'd guess a good bit of that was on break-in and it stuck to the magnet and stopped flowing.

 

Factory spec was 75w-85, but all I could find locally was 75w-90. Shelled out for Amsoil 75w-90 synthetic "Severe Gear" gear oil. I reckon I'll check it in another 30k.

 

How often do you guys drain your differential? I drive mostly highway and tow about 3 times a year.

 

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TXGREEK Senior Enthusiast

TXGREEK

Posted
Posted

Changed my rear differential fluid today at 52,000, first change on my 2017.
 
Metal shaving sludge was moderate, I'd guess a good bit of that was on break-in and it stuck to the magnet and stopped flowing.
 
Factory spec was 75w-85, but all I could find locally was 75w-90. Shelled out for Amsoil 75w-90 synthetic "Severe Gear" gear oil. I reckon I'll check it in another 30k.
 
How often do you guys drain your differential? I drive mostly highway and tow about 3 times a year.
 
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Did you pop off the Rear Diff Cover and reinstall it then filled?

I switched my Rear Diff Cover to the Brute G2 last year and absolutely LOVE IT! Super easy to drain and refill without having to do all that work. I swapped out the Rear Diff Cover 8k miles ago and then just a couple days ago with the Amsoil 75w90 added Amsoil Slip Lock as well even though it’s already got some in it, won’t hurt anything.


eefe5ed31d79bf722537c6785b0e2a32.jpg

I’d do it no later than every 20k, better safe than sorry!



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TXGREEK Senior Enthusiast

TXGREEK

Posted
Posted

Btw, the front differential is much easier than the rear unless you’ve got a G2 Brute and don’t forget (only on 4x4’s) your transfer case too which takes transmission fluid (Amsoil)


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HeySkippyDog Senior Enthusiast

HeySkippyDog

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Hey there, my TX friend!

I did remove the cover fully, sprayed it with brake clean and wiped it down. Also wiped down the axle flange before reinstalling.

I am 2wd, so no need to do the front. I was under the impression these G80s did not like additives, so I ran the Amsoil as it came. The pumpkin took about 2 and 3/4 quarts before it weeped out of the fill hole. The manual said to go until 1mm below, but I figured what the hell. The old way was to fill until weep, it's got a vent tube. If it's too much, it'll blow out.

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TXGREEK Senior Enthusiast

TXGREEK

Posted
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Hey there, my TX friend!

I did remove the cover fully, sprayed it with brake clean and wiped it down. Also wiped down the axle flange before reinstalling.

I am 2wd, so no need to do the front. I was under the impression these G80s did not like additives, so I ran the Amsoil as it came. The pumpkin took about 2 and 3/4 quarts before it weeped out of the fill hole. The manual said to go until 1mm below, but I figured what the hell. The old way was to fill until weep, it's got a vent tube. If it's too much, it'll blow out.

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I’m kinda OCD about anything with gears etc, the rear limited slips “ALWAYS” need the additive but you should be ok cause the Amsoil gear oil already has some in it, I just added some for added insurance lol. That’s great that you did it, in a way, you’re lucky cause you don’t have the added maintenance of the front differential and transfer case.


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txab Senior Enthusiast

txab

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Correct, the G80 does not require any additional friction modifiers. In many cases additional friction modifiers can cause to act erratically. In fact GM specifically states no additional modifier to be added.

HeySkippyDog Senior Enthusiast

HeySkippyDog

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Correct, the G80 does not require any additional friction modifiers. In many cases additional friction modifiers can cause to act erratically. In fact GM specifically states no additional modifier to be added.
That's what I had heard, and what drove me to the Amsoil. Every other brand advertised additives for limited slip.

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TXGREEK Senior Enthusiast

TXGREEK

Posted
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Correct, the G80 does not require any additional friction modifiers. In many cases additional friction modifiers can cause to act erratically. In fact GM specifically states no additional modifier to be added.


Yeah, I heard about that too but originally when had my Rear Diff switched out I had the Slip Lock added to the Lucas gear oil and just last week when I ordered multiple boxes of Amsoil I added Slip Lock. At least it’s going to take me 5 minutes to drain and refill with the G2 Brute Diff Cover. Thanks TxAb!


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txab Senior Enthusiast

txab

Posted
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You say "rear diff switched out", do you mean diff gears or just cover? If swapped to something other than a G80 then modifiers might be appropriate. check manufacturer's specs. I've heard no changes to GM's longtime recommendations for their G80

HeySkippyDog Senior Enthusiast

HeySkippyDog

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You say "rear diff switched out", do you mean diff gears or just cover? If swapped to something other than a G80 then modifiers might be appropriate. check manufacturer's specs. I've heard no changes to GM's longtime recommendations for their G80
I've always heard that the Eaton hates the LSD additives.

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txab Senior Enthusiast

txab

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Generally causes them to chatter. At least that's what's been reported here. Also locking when not necessary. I'm sure some have had no issues that they've noticed.

Mike GMC Enthusiast

Mike GMC

Posted
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The G80 is a locker, not a limited slip diff(LSD).  I don't know what the additive would do to the locking mechanism, but my guess is nothing, it certainly does not need it.

 

To answer the original question, every 50kwith the Amsoil would be fine. I will be changing out the factory fluid at 10-20k.  Just want to get the break in oil and junk out if the case.  Was the factory oil milky?  I've heard that's from the gear marking compound used to set up the gears.  It's not supposed to hurt anything, but it can't hurt to get it out.

TXGREEK Senior Enthusiast

TXGREEK

Posted
Posted
The G80 is a locker, not a limited slip diff(LSD).  I don't know what the additive would do to the locking mechanism, but my guess is nothing, it certainly does not need it.
 
To answer the original question, every 50kwith the Amsoil would be fine. I will be changing out the factory fluid at 10-20k.  Just want to get the break in oil and junk out if the case.  Was the factory oil milky?  I've heard that's from the gear marking compound used to set up the gears.  It's not supposed to hurt anything, but it can't hurt to get it out.


Mine wasn’t milky at all but dark color. The Amsoil 75W90 was very clear.


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TXGREEK Senior Enthusiast

TXGREEK

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The transfer case was dark too and lots of metal shavings as thick as a human hair and the magnet was covered with it. Btw, very strong magnet too


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