CHECK YOUR DIFFS...

[Pryme]

5 hours ago, Black02Silverado said:

I always change mine over to AMSOIL right away.  These Easy Packs make it nice and clean to do. 

I just bought the 75w90 severe gear in the easy quarts. They were 17.29 each from the local dealer. Is that pretty much the going rate? 
 

 

[Pryme]

2 hours ago, newdude said:

 

 

 

3.17 quarts.  Fluid should be 0 – 10 mm (0 – 0.4 in) from the bottom of the fill hole.  All level checking and filling should be done with the vehicle level so axle supported by stands or vehicle on a 4 post drive on lift or parked on flat level ground when checked and filled.  Also, if driven prior, wait 5 minutes for drainback from the axle tubes.  

Okay so the 11.5” in our trucks is level with fill hole or a max of .4? So my new truck is low on rear differential fluid, nice. 
 

my garage is pretty much spot on flat. It was about .8-.9” down from fill hole. 
 

What is the spec for the front? To the fill hole also? 
 

does gm specify anything in particular about the gear lube or just a synthetic 75w90 like this amsoil severe gear?

 

It would be nice if there was a drain plug but is there any reason a guy couldn’t mitivac the old fluid out?

 

thank you 

[newdude]

12 minutes ago, Pryme said:

Okay so the 11.5” in our trucks is level with fill hole or a max of .4? So my new truck is low on rear differential fluid, nice. 
 

my garage is pretty much spot on flat. It was about .8-.9” down from fill hole. 
 

What is the spec for the front? To the fill hole also? 
 

does gm specify anything in particular about the gear lube or just a synthetic 75w90 like this amsoil severe gear?

 

It would be nice if there was a drain plug but is there any reason a guy couldn’t mitivac the old fluid out?

 

thank you 

 

 

Front is 1.9 quarts.  Fluid should be 0 – 6 mm (0 – 0.24 in) to the fill hole.  

 

As for fluid, GM uses 75w85 synthetic for the front, 75w90 for the rear.  You can use 75w90 for both though.  

 

It must be a cost cutting move as the fronts on these used to have both a drain and the fill instead of just a fill plug.  

[Pryme]

9 minutes ago, newdude said:

 

 

Front is 1.9 quarts.  Fluid should be 0 – 6 mm (0 – 0.24 in) to the fill hole.  

 

As for fluid, GM uses 75w85 synthetic for the front, 75w90 for the rear.  You can use 75w90 for both though.  

 

It must be a cost cutting move as the fronts on these used to have both a drain and the fill instead of just a fill plug.  

So my front is pretty much on. 
 

the rear used to have a drain too at one point. Silly it no longer does. 
 

Thanks for the valuable info. Is it right out of the service manual for the 2020+

 

some trucks you remove the lower cover bolt to drain fluid? Is that not the design here?

 

 

Edited March 27, 2023 by Pryme

[gemarsh]

Thank you @newdude for the information. I have turned wrenches for 41 years come Thursday. I have never seen a fill hole on briggs&Stratton to a 13 speed eaton transmission not be the full mark. If gm wants it to be filled under the fill hole, lower the damn hole.

[gemarsh]

33 minutes ago, Pryme said:

 

 

It would be nice if there was a drain plug but is there any reason a guy couldn’t mitivac the old fluid out?

 

 

A mitivac would work in a worse case scenario. 1. You won't get the break-in glitter out. 2. You'll be a stinky gear lube mess by the time you get 3qts sucked out.

 

From what I have read, the rear cover uses a reusable gasket.

 

When you spray the housing out with brake kleen, catch the mess on a clean white paper towel and let us know if you have much glitter, please.

 

Don't plan on draining until 45k miles. With 7 trucks at my disposal it might be awhile for me.

[gemarsh]

I haven't seen everything, but the only rear axles that I can recall that have a drain plug were the axles that didn't have a diff cover.

[Pryme]

7 minutes ago, gemarsh said:

A mitivac would work in a worse case scenario. 1. You won't get the break-in glitter out. 2. You'll be a stinky gear lube mess by the time you get 3qts sucked out.

 

From what I have read, the rear cover uses a reusable gasket.

 

When you spray the housing out with brake kleen, catch the mess on a clean white paper towel and let us know if you have much glitter, please.

 

Don't plan on draining until 45k miles. With 7 trucks at my disposal it might be awhile for me.

Yeah I thought about the glitter not coming out. Dropping the cover would be the right way. 
yes, I will for sure document that. 

[Black02Silverado]

1 hour ago, Pryme said:

I just bought the 75w90 severe gear in the easy quarts. They were 17.29 each from the local dealer. Is that pretty much the going rate? 
 

 

That is a good deal.

[KARNUT]

1 hour ago, gemarsh said:

Thank you @newdude for the information. I have turned wrenches for 41 years come Thursday. I have never seen a fill hole on briggs&Stratton to a 13 speed eaton transmission not be the full mark. If gm wants it to be filled under the fill hole, lower the damn hole.

My 02 avalanche has a drain plug. Much to my surprise you don’t fill until it runs out. Of course my 1974 barracuda took atf instead of gear oil and my 1994 V-10 Rams 5 speed took 50WT if memory serves. I always check so I’m not surprised. 

[Pryme]

I wish I could find a service manual for the 2020+ trucks. Not even Haynes or Chilton has one. 
 

They obviously have one as the dealership has to have them. 
 

I want to find out the torque specs and tightening sequence for the diff cover and if the gasket is indeed reusable, before I remove it. 
 

newdude, do you happen to have that information or a screenshot of that page in the manual?

 

thanks

[Grumpy Bear]

3 hours ago, Pryme said:

I wish I could find a service manual for the 2020+ trucks. Not even Haynes or Chilton has one.

 

Next new anything I buy is sitting in bubble wrap for 5 years until the aftermarket catches up. 

[Pryme]

5 hours ago, gemarsh said:

I haven't seen everything, but the only rear axles that I can recall that have a drain plug were the axles that didn't have a diff cover.

The HD trucks right before the 2020+ had drain plugs. I saw a couple videos online of ppl draining them and refilling. 
 

 

[Pryme]

So I called for pricing on the diff cover gasket and fill plug gasket. 32 and change for the cover gasket and 4.98 for the tiny plug gasket. 
 

I am pulling the trigger on the big Mityvac because I’ve wanted one anyway. It’s not the small brake bleed pistol it’s the big 2.3gal MV7201. It will suck out 3qts lickity split. 
 

I can use it around the garage for small engine oil changes and atvs etc. 

 

Can do a trans or anything very quickly. 
 

As long as a guy has everything ready to go and comes back from a drive, the fluid should have all the glitter suspended and can be pretty much removed quickly as it only takes seconds to remove the fill plug. 
 

 

[64BAwagon]

I did my 2021 3500 rear diff and the cover gasket is definitely reusable. When I serviced it I pulled the cover plate off and painted it also. 

The first change I always pull the cover so I can wipe the inside of the case out. I dont spray the gears down with cleaner because I have always felt that the residue from the cleaner would have an effect on the new fluid. I cant prove it but I just avoid it in case. For me, cleaning the magnet and wiping out the bottom of the case is enough. 

I caught a sale at Auto Zone over a year ago that had Delo full syn 75W90 gear oil for less than $9 a qt so I stocked up. Rural king also has Mystik full syn for a good price. 

 

Edited March 29, 2023 by 64BAwagon