X-fer case, diff fluid change?

[papageoff]

I've got about 61k on the truck and as far as I know these fluids have never been changed.  I have a trip to NC coming up in a couple weeks and was thinking about changing them.

 

Worth bothering?  Do I need any special fluids like a friction modifier for the t-case clutches?

[Black02Silverado]

No special additives needed.  You just need Dexron VI for the transfer case.  Now would be a great time to change them out. 

 

Differential, Front 8.25 RG......GL-5
     All TEMPS......80W-90
         SAE 80W-90 Synthetic Gear Lube (AGLQT)
         Severe Gear® 75W-90 (SVGPK)
         Severe Gear® 75W-110 (SVTQT)
Differential, Rear 8.6 RG......GL-5
     All TEMPS......75W-85 [2]
         Severe Gear® 75W-90 (SVGPK)
Differential, Rear 9.5 RG......GL-5
     All TEMPS......75W-85 [2]
         Severe Gear® 75W-90 (SVGPK)
Transfer Case,MP 3023/3024......AF6
         Signature Series Fuel-Efficient Synthetic Automatic Transmission Fluid (ATL) (ATLQT)
         OE Fuel-Efficient Synthetic Automatic Transmission Fluid (OTLQT)
Transfer Case,MP 1625/1626......AF6
         Signature Series Fuel-Efficient Synthetic Automatic Transmission Fluid (ATL) (ATLQT)
         OE Fuel-Efficient Synthetic Automatic Transmission Fluid (OTLQT)
Transfer Case,MP 1222, 25,26......AF6
         Signature Series Fuel-Efficient Synthetic Automatic Transmission Fluid (ATL) (ATLQT)
         OE Fuel-Efficient Synthetic Automatic Transmission Fluid (OTLQT)

 

CAPACITIES: Engine, with filter..........8 quarts [1] Cooling System, Initial Fill..........16.9 quarts Passenger Car & Light Truck Antifreeze & Coolant AMSOIL Antifreeze and Engine Coolant Automatic Transmission, 6L80 Initial Fill..........6 quarts Automatic Transmission, Total Fill    6 speed LD 6L80..........12.2 quarts    6 speed W/ HD Cool 6L80..........12.4 quarts Differential, 8.25 RingGear Front..........3 pints Differential, 8.6 RingGear Rear..........4.2 pints Differential, 9.5 RingGear Rear..........5.5 pints Transfer Case, MP 1625/1626..........3.2 pints Transfer Case, MP 3023/3024..........3.2 pints Transfer Case, MP 1222, 25,26..........3.2 pints [1] After refill check oil level.

TORQUES:    Oil Drain Plug.....18 ft/lbs    Transfer Case      Fill Plug 13 ft/lbs      Drain Plug 13 ft/lbs

[papageoff]

Heh... I feel like you've answered this before.  ;-)

 

Not that it seems to matter from a lubricant standpoint, but is there a way to know which of those transfer cases I have without climbing under there and looking for stampings?  

 

Also, what is the difference between the signature series vs the "OE fuel efficient" one.

 

[Black02Silverado]

1 hour ago, papageoff said:

Heh... I feel like you've answered this before.  ;-)

 

Not that it seems to matter from a lubricant standpoint, but is there a way to know which of those transfer cases I have without climbing under there and looking for stampings?  

 

Also, what is the difference between the signature series vs the "OE fuel efficient" one.

 

You should be able to find which transfer case by getting with the dealer with your VIN. 

 

The difference between the Signature Series and O.E. is that the Signature Series is a PAO based stock and the OE is a Group III,  in other words a PAO is full synthetic and Group III is a hydro-cracked petroleum base stock.  Plus the SS has a better additive package and is why it is an extended drain oil.  The OE is recommended to be changed out in accordance with the manufacture recommendation.

[SteveCZ]

Or just stay with stock.... biggest thing is to get the old nasty stuff out and fresh in.   

[Snowcamo]

I read a thread from a while back on a Chevy site where a guy suggested 80-90 for front and rear differentials no question. Said it holds up better and will prevent rear failures like the one's that have happened. Any input on this?

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[Black02Silverado]

8 minutes ago, Snowcamo said:

I read a thread from a while back on a Chevy site where a guy suggested 80-90 for front and rear differentials no question. Said it holds up better and will prevent rear failures like the one's that have happened. Any input on this?

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 A 75w-90 will work just fine.  I'm running that in my 2002 and have 185k on it now.  If you run any good quality gear oil, synthetic being what is recommended you will not have any issues.

[SSchup]

I just did my 2018 this weekend with 8K miles on it. Did front and rear Difs with the Severe gear 75W-90 and the transfer case with the Signature series  ATF. The factory stuff that came out of the front dif was nasty looking.

Also the transfer case factory fill wasn't pretty either, along with lots of metal shavings on the plug.

[300 Blackout]

I changed to Amsoil 75W-90 Severe Gear after getting new gears at 70k. Very happy so far. I also bought 15 quarts of Signature Series Fuel Efficient ATF (ATLQT-EA) to change my trans and transfer case fluid (15 quarts is more than enough and leaves a little extra in case you spill). If you’re going to drop that much on Amsoil, you’ll save a lot by getting a preferred membership.

 

Someone else in this thread said the fluid going in isn’t as important as getting the old fluid out. I tend to agree with this, however, these fluids only get changed every 50-100k. My thought with such a long change interval is that I might as well use the best. An extra $50 for fluid that will last 50k miles is 0.1 cents/mile.

 

[papageoff]

I agree with using the best. I've usually been a mobile1 guy, but I have used amsoil in my bike's rear diff a couple times. Never had a problem.

I'm totally game for using it this time. My wife will tell you... I love this truck.

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[papageoff]

Anyone know the rpo codes for which rear diff I have? It's a 15 z71 5.3.

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