Trans, x-case, diff fluid changes???

[heiner921]

My (new to me) 15 silvy has just hit 80k. According to records, the trans, diffs, and x-case fluids have never been changed.

Trans has no shifting issues, but fluid is brown on dipstick

Best way to do a fluid change with filter and get more than have the fluid changed?  What fluid does it take?
Reccomendations on adding a drain plug? (I dont wanna buy a $300 pan)

Also how often should diffs and x-case be changed?

[LDM]

What transmission do you have?  The 6 speed takes Dexron VI while the 8 speed should use the new Mobil 1 LV HP fluid.

 

I just did the transfer case, front, and rear differentials on my truck a couple weekends ago.  Used 75W90 in both differentials and Dex VI in the transfer case.  I also just had my dealership perform the TSB on my 8 speed transmission due to the hard 1-2 shift when cold, so my transmission also has a new filter and fluid for free thanks to the TSB.  So far it has fixed the very annoying hard 1-2 shift.

[CamGTP]

If you do all the fluids now, you shouldn't have to do again for another 80k miles at least.

 

Some people will do it much sooner but that is their call. I'm not one of those people.

[2018GMC]

52 minutes ago, LDM said:

What transmission do you have?  The 6 speed takes Dexron VI while the 8 speed should use the new Mobil 1 LV HP fluid.

 

I just did the transfer case, front, and rear differentials on my truck a couple weekends ago.  Used 75W90 in both differentials and Dex VI in the transfer case.  I also just had my dealership perform the TSB on my 8 speed transmission due to the hard 1-2 shift when cold, so my transmission also has a new filter and fluid for free thanks to the TSB.  So far it has fixed the very annoying hard 1-2 shift.

If trans has a dipstick its a 6 speed. 8 and 10 speed = no dipstick unfortunately 

 

How many miles on you 8 speed when you had fluid flushed? I have 11k on mine and it shifts fine. If it acts up will get it flushed or before the powertrain warranty expires. 

 

Wonder if there is an expiration on the TSB?

[Black02Silverado]

1 hour ago, heiner921 said:

My (new to me) 15 silvy has just hit 80k. According to records, the trans, diffs, and x-case fluids have never been changed.

Trans has no shifting issues, but fluid is brown on dipstick

Best way to do a fluid change with filter and get more than have the fluid changed?  What fluid does it take?
Reccomendations on adding a drain plug? (I dont wanna buy a $300 pan)

Also how often should diffs and x-case be changed?

Now is a good time to change them all.  The transmission there are videos on Youtube that show how to change out the filter as well as to do a complete fluid exchange.

 

Good info posted above on the type of fluid.  You can run AMSOIL's ATL in the transmission as well as the transfer case.  AMSOIL's Severe Gear 75w-90 in the differentials.  I've changed out the fluid to AMSOIL when I first get my trucks at about 8k miles and then again at 100k.  I have UOA's showing great results and I even tow a 4k lbs trailer.

 

As for the drain plug on the transmission, you can add one to the existing pan.  There are drain plug kits you can get at Auto Zone and such or even Summit Racing.  I got a drain plug from Summit Racing and had it welded into my pan.  That way I don't have to worry about it leaking which isn't an issue but I just like the fact of it being welded in.  Good to know people that can Tig Weld.

 

If you are interested in AMSOIL, shoot me a PM with your address and what you want and I can get you a quote delivered to your door.

[TJW317]

I did the transmission fluid in a 2015 Suburban yesterday.  All I can say is good luck.  You'll see the videos of people bracing a 2x4 against the frame cross sections and then putting a ratchet strap around the exhaust near the flex pipe and then ratcheting the pipe down to give you the clearance needed to get the pan out.  You have to give it everything you got to get that exhaust  cross section to move maybe a quarter inch and even then you get maybe 1/32" of clearance to pull the pan.  Engineering at its finest.

 

Thankfully I had purchased a spare pan and had someone tig-weld an O2 sensor bung onto it so I won't have to go through that again for a while.  I figure in 500 miles or so, I'll do a drain and fill and then again in another 500 miles.

[LDM]

15 hours ago, 2018GMC said:

If trans has a dipstick its a 6 speed. 8 and 10 speed = no dipstick unfortunately 

 

How many miles on you 8 speed when you had fluid flushed? I have 11k on mine and it shifts fine. If it acts up will get it flushed or before the powertrain warranty expires. 

 

Wonder if there is an expiration on the TSB?

Not sure on an expiration, my truck has a little over 37K.  Not sure if TSB only apply under warranty or not but my dealership didn't give me any issues having it done.  I'm still in the powertrain warranty though. 

[heiner921]

10 hours ago, TJW317 said:

I did the transmission fluid in a 2015 Suburban yesterday.  All I can say is good luck.  You'll see the videos of people bracing a 2x4 against the frame cross sections and then putting a ratchet strap around the exhaust near the flex pipe and then ratcheting the pipe down to give you the clearance needed to get the pan out.  You have to give it everything you got to get that exhaust  cross section to move maybe a quarter inch and even then you get maybe 1/32" of clearance to pull the pan.  Engineering at its finest.

 

Thankfully I had purchased a spare pan and had someone tig-weld an O2 sensor bung onto it so I won't have to go through that again for a while.  I figure in 500 miles or so, I'll do a drain and fill and then again in another 500 miles.

Pic of where on the pan u put the bung?  And is the bung on the inside or outside for clearance?

[Black02Silverado]

Here is the drain plug I installed on our 2016 Suburban.

[swathdiver]

Every 50K for all, especially the transmission.  My fluid only has about 5-10K of life left in it and it is at 36K.  Not waiting, changing any day now as time allows.  Basically, follow severe service schedule.

[Doublebase]

I did a pan drop and filter on my 2018 6speed at 45,000 miles or so, but I did a simple fluid exchange after my first year (25,000 miles). 
 

And that’s what I do, I change everything but the coolant once a year whether it needs it or not. What’s it cost me to do my diffs, tranny and transfer case? $50-$60 bucks? I think it’s worth it. 

[Doublebase]

On 3/25/2020 at 10:18 PM, Black02Silverado said:

Here is the drain plug I installed on our 2016 Suburban.

Wow, that's nice work, did you weld that in?

[Black02Silverado]

1 hour ago, Doublebase said:

Wow, that's nice work, did you weld that in?

Yes, welded it in and the clearance inside the pan is minimal.  No issues with it touching the transmission.