Differential & Transfer Case Fluid Change/Flush

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ShawnQ

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I have my 2007 Tahoe in the dealer now for a rear main seal leak, and a pinion seal leak. Both are covered under warranty.

They told me that I should probably change the front and rear diff fluid, as well as the Transfer Case fluid while it is in there. However, this is NOT covered under warranty.

They are wanting almost an additional $500 to have this done. Seems RIDICULOUS! Their reason for the high cost was that they 'flush' the old fluid, not just drain and fill. Sounds like a gimmick to me. I'm pretty sure that draining and filling is just fine (and probably what most people do).

Is it worth it to let the dealer do this, or should I do it myself?

How much fluid, and what type, do I need for a 2007 Tahoe Z71?

Thanks in advance,
Shawn
 

99_Yukon

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Differential & Transfer Case Fluid Change/Flush

There is no reason to flush, drain and fill is just fine. You could have a quick lube place do the same thing for about $160-$180. Or as you said do it your self but there is probably no drain on the rear, have to suck it out. The fluid is probably 75w-90 in front and rear, maybe 80w-90, and ATF in the transfer case.
 

BRUTUS_T_HOG

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Total scam. Drain and fill will be just fine if everything is working ok.

The front and rear differential takes synthetic gear oil, the transfer case takes about 3qt of Auto Trak II fluid if you have an auto 4WD button, or ATF if you do not.

You can tell by the fluid color, Auto Trak II is blue and ATF is red.

Do not put ATF in a t-case that calls for auto trak, the t-case has an internal clutch that requires the special blue fluid
 

FishinCricket

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GM's advice in the owners manual is to "service" the Transmission.. They DO NOT recommend "flushing" it. Ever.

This is my understanding of it, related to me by our GM warranty administrator.
 

carrolldad

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ATF vs Front Differential in a 2002 yukon xl

This may be a dumb question, but isn't the transfer case and front differential the same thing?
 
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BRUTUS_T_HOG

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This may be a dumb question, but isn't the transfer case and front differential the same thing?

The front differential is the axle and is connected to the front wheels.

The transfer case mounts behind the transmission and sends power to the rear axle in 2wd and sends power to the front and rear axle in 4wd mode

---------- Post added at 06:50 PM ---------- Previous post was at 06:48 PM ----------

GM's advice in the owners manual is to "service" the Transmission.. They DO NOT recommend "flushing" it. Ever.

This is my understanding of it, related to me by our GM warranty administrator.

Flushing won't hurt it when using only fresh fluid. Some places will try to sell you on adding their special flushing cleaning agent.. thats what does the damage or knocks dirt loose to make valve body stick
 

carrolldad

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The front differential is the axle and is connected to the front wheels.

The transfer case mounts behind the transmission and sends power to the rear axle in 2wd and sends power to the front and rear axle in 4wd mode

Thanks, so if one has put auto trac II in the front differential is that bad? I have not driven but 3 miles since.
 

BRUTUS_T_HOG

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Thanks, so if one has put auto trac II in the front differential is that bad? I have not driven but 3 miles since.

That is bad, but if you drain it out and add the correct gear oil back to the axle it will be ok. If you drove in 2WD mode the differential gear would never have even turned so they couldn't be damaged.
 

carrolldad

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That is bad, but if you drain it out and add the correct gear oil back to the axle it will be ok. If you drove in 2WD mode the differential gear would never have even turned so they couldn't be damaged.

Thanks for the reply. I did put it in 4wd for a short time. I ended up draining it, put Mobil 1 75/90 in it. then drove for a day then drained and refilled.
 

Hurlz07Tahoe

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How do I tell if I have the BW 4485-NR3 - Transfer Case which takes DEXRON(R)-III, GM P/N 12346143 or the NVG 246-NP8 - Transfer Case which takes Auto-Trak II, GM P/N 12378508?
 

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