Changing your transfer case fluid

Changing your transfer case fluid

Posted on 28. Jan, 2009 by in How To

This article was originally submitted in 2004 by Tom Fraley aka MountaineerTom. Thanks Tom!

Changing the transfer case fluid is a pretty straightforward job. If you have the manual transfer case (lever actuated), use DEXRON-III Automatic Transmission Fluid. If you have an automatic transfer case (push button actuated), you should use the fluid that GM recommends. Some owners’ manuals may say to use Automatic Transfer Case Fluid (GM Part No. 12378396), which is a reddish colored fluid. GM has a new Auto Trak II Transfer Case Fluid (GM Part No. 12378508), which has a bluish color to it. The newer fluid has better friction modifiers. While your doing the job, it’s a good idea to change the drain and fill plugs (GM Part No. 15032997) out too.

Transfer Case Fluid

Auto Trak II Transfer Case Fluid (Part No. 12378508) and Replacement Drain Plugs (Part No. 15032997)

First thing you should do is remove the transfer case skid plate for easier access. Only four bolts to remove. (15mm)

Remove Skid Plate Bolts

Remove Skid Plate Bolts

After removing the skid plate, the drain and fill plugs (18mm) will be very easy to get to. Remove the plugs and let the old fluid drain out. Be ready for the fluid to shoot out pretty far, so keep that in mind when positioning your drain pan.

Plug Locations

Plug Locations

All that is needed to do now is reinstall the drain plug, torque to 15 ft. lbs., and refill the transfer case with fluid until the fluid level is even with the bottom of the fill hole. Basically, fill it up until the fluid runs out the fill hole. It takes almost 2 quarts to fill it up. To make the fill up easier, you may want to purchase a pump at a local auto parts store. These are very handy, don’t cost a lot, and will fit on gear oil bottles for when you go to change your differential fluids.

Drain then refill

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36 Responses to “Changing your transfer case fluid”

  1. milo thornton

    05. Oct, 2009

    you are wrong (but not the only one!) on the description of auto v manual transfer cases.
    all gm transfer cases (my research in the context of silverado 2500hd) which have push button select are manual transfer cases.

  2. Mitch Rapp

    13. Feb, 2010

    Just did this and the instructions were excellent. Thanks. It took just about 2 full qts before the fluid began running out of the fill hole. At $11.49/qt at the dealer for Auto-Trak II fluid, I didn’t want to spill a drop.

    According to my dealer, you can identify the the Automatic Transfer case by the 4 push button switches on the dash. The big round “Auto 4WD” switch is the key and indicates that you need Auto-Trak II fluid. Of course the other switches are 2HI, 4HI and 4LO. If you don’t have the Auto 4WD button, it is considered a manual transfer case.

    My truck is a 2001 GMC Sierrra that I just bought with 142,000 miles on it. Decided to change all the fluids since I didn’t know when they were previously changed. I was shocked to find less than a pint of fluid in the transfer case when I drained it!!!!

  3. Dave Hare

    19. Jun, 2010

    I own a 2007 Silverado 2500HD. I looked in the owners manual and it says the transfer case uses GM DEXTRON IV fluid which is the latest automatic transmission fluid. This Silverado has the electronic dial type 4×4 switch on the dash near the AC controls. Q, Why do I need to replace the drain and fill bolts?

  4. Doug

    27. Aug, 2010

    These intructions were perfect, did the drain and refill in less than 30 minutes. Thanks

  5. Aron

    19. Feb, 2011

    @ Dave, I have a 2008 Silverado with the same Auto Transfer Case. My brother is a mechanic and he told me that you must use the dealer (GM) fluid. If you are not sure which one to use just go to the parts shop at your local dealer and give them your VIN. They will tell you exactly what you need and how much. I am going to be changing mine in the next couple weeks. Goood Luck.

  6. Wes

    07. Mar, 2011

    I just bought a Chevy Tahoe 2001,
    Did a transmission rebuild on it…
    Being stationed in Germany I don’t have access to the GM Auto Trak II Transfer Case Fluid in a timely manner,
    after much research i have found that many people say you can SUB the Auto Trak II with Royal Purple Synchromax……
    Any thoughts on this?

  7. Justin

    25. Mar, 2011

    I am a certified automotive technician, I deal with lube jobs and fluid changes all day. I would not suggest ever putting Royal Purple Synchromax in your transfer case. If you cannot access the recommended transfer case fluid found in your owner’s manual, I would suggest that you go down to the nearest lube or auto shop and ask if they carry anything for your type of transfer case. If you cannot find anything specifically for your type of truck, I would then suggest that you ask at the same shop what the closest fluid would be and try that. All fluids will have similar effects and results, The problem occurs where the power is transfered from your engine to the drive shaft, depending on the power put into the transfer case, you will need a fluid with more or less friction retardant addatives as well as various others. So if it is for a short time (not exceeding 45000 km or 3 months) I would say that the closest fluid compatability with your make and model would be the best solution as opposed to the Royal Purple Synchromax as it is a transmission fluid and could even slow down the gears inside your transfer case resulting in loss of power to the wheels or ultimately, complete disfunction or shut down of the power transfer case which would be a very expensive fix in any 4X4 vehicle. I hope this helps, and if you have anymore questions dont hesitate to ask.

  8. Don

    27. Mar, 2011

    Thanks to these instruction, I feel like I will be able to do this very easy. But I have a question. When I purchased my 2004 tahoe it did not have the owners manual with it. So how often should I change the fluid in the transfer case and in the front and rear differentials?

  9. breaz25

    07. May, 2011

    It has been recommended to me to make sure you can remove the fill plug prior to removing the drain plug. You don’t want to drain the fluid and then find out you can’t fill it back up!!! :-)


    03. Jun, 2011

    How often should I change the transfer case oil in my 2004 Tahoe ? Does it make a difference if I never have used my 4 wheel drive ?
    How often do you I have to change the front and rear differential ? The owner Manuel does not show a recommendation. Is the factory oils used put in these vehicles when new have synthetics in them ?

  11. fred

    11. Jun, 2011

    acording to my transfer case on my 2001 gmc sierra c3 it says to use 30 wt.motor oil.the problem im having is when it gets hot it locks up causing the front wheels to bind when i turn this is a all wheel drive truck

  12. Alain

    12. Jul, 2011

    I don’t want to be an ass, but I seriously doubt that it says to put 30 wt motor oil. I own a 1500 HD Sierra SLT 4X4 with AWD (all wheel drive) I must not put anything but the blue oil that I have found only at GM. If you don’t have AWD Maybe you are right……..

  13. david

    14. Jul, 2011

    i have a 2001 gmc c3 doing same thing when hot feels like jumping in sharp turns. Had gm dealer change to new fluid only avail there didnt help. Did u fix yours fred

  14. Dan

    19. Jul, 2011

    Hello gents,
    I have a 2008 GMC Sierra, w/electronic 4×4. All newer GM trucks require Dexron VI (“6″). (Duramax may be different.) It’s basically a fully synthetic automatic transmission fluid that is used strictly in GM vehicles, mostly as of 2003. It’s only $4-$6 canadian per 1 liter. Made by Castrol.

    By the way thanks for the instructions!
    Oh and front and rear axles use Synthetic SAE 75W-90. just FYI.

  15. Erick

    24. Jul, 2011

    I just got a c3 about 2 week and is doing the same went it gets hot front is like jumping David did u fix urs n how ???

  16. Gary Conlon

    03. Aug, 2011

    2007 Chev Suburban LTZ 6.0

    Great post exactly as described. This was particularly helpful after I had already took the FILL plug out and much to my surprise at least 3 quarts drained from the fill plug!!!! This vehicle has only been serviced by the dealer. It might have even come from the factory that way. In addition it was red fluid – WTFO. (Do I need to be concerned about my transfer case after running 50K miles with an extreme overfill of the wrong fluid?) Your picture reassured me that I hadn’t somehow drained the transmission – duh. I am distressed with the lack of quality and over-priced work done by the dealer or factory. This Beautiful truck was just in the shop for a warranty tranny leak and it just started leaking again. I will always try to do it myself to make sure it is done right! They would’ve charged my somewhere around a grand for the diffy.transfer fluid changes. However I will be back to the shop for the tranny leak and would like to discuss the transfer case with the service manager Sorry for the rant.

    I used just over 2 quarts Lucas Syn 75w 90 in the front Diff
    2 quarts Autotrac II in the transfer case
    almost 4 quarts Lucas Syn 75W 90 Rear

    Thanks again

  17. Eric

    03. Aug, 2011

    I have a 2005 Trailblazer with more than 60,000 miles on it. The Service 4-wheel drive warning light came on today and then turned off. I am guessing that I will need to change the fluid in the transfer case? What do you think? Also, is that an easy thing to do? I change my own oil and brake pads, but have never tackled a transfer case. Any thoughts?

  18. Brandon

    25. Feb, 2012

    Very helpful info thanks!

  19. John

    10. Apr, 2012

    I have a 2007 Denali. The manual says I have to use one which is reddish. When you say it is recommended to use the bluish part# 12378396,
    does that mean I should stop using the reddish one? Will using the former do any harm. Thanks a lot for your help. Looking fowrward to hearing your response.

  20. CHRIS

    18. Apr, 2012

    NVG 236 and 246 ……………………….. Auto-Trak II Fluid Gm P/N 12378508NVG 261 and 263 …………………. Manual Transmission Fluid GM P/N 88861800


  21. paul

    20. Apr, 2012

    Some GM transfer cases (1998-2007) suffer from a condition called transfer case pump rub (GM service bulletin 1962218). Although GM is aware it is a problem they never issued a recall. Merchant Automotive has a kit to fix it. I would strongly suggest going to their web site & find out if yours is affected. If so take pre-emptive action unless you want a very expensive repair job in future.

  22. Tom

    09. Jun, 2012

    @paul mine just started leakin on my 2000 silverado. I have a warrentee witch is covering the $956 fix so yes u r right I is VERY expensive

  23. Steve

    16. Jul, 2012

    The term “pump rub” is kind of like a “pinch point”–both sound fairly benign, but can kill you.

    Pump rub has disabled my 2001 Silverado that has less than 200,000 miles on it.

    Dealer’s service rep said, “We’ll fix it with a new/rebuild with a three-year waranty for $2,000.”

    GM rep said, “We’ve never heard of one having that problem before.”

    So word to the wise: Keep a close eye on your transfer case fluid level, and if you begin to lose any, have it checked for a leak. If you catch it soon enough you can have a relatively inexpensive patch job w/ JB weld done on the housing, and the innards won’t have been damaged.

    Patch job won’t solve the problem, but will give you some time to figure out your next move.

  24. sef

    30. Aug, 2012

    yes, you can do anything u set your mind to especially doing minor repairs yourself. there are websites that , once you google your issue, it will direct u to specific websites 2 help u w/ your problem step by step. So don’t b mad when u feel like u got ripped off at a dealership when u more than likely could have did a minor repair yourself. Always search for info from many sources to get a good idea of what project u are about 2 take on. Believe you can do it , heck even your local dealer technician didn’t know anything about cars or trucks at one time. They had 2 learn it and so can u!!!!!!!!!!!

  25. Wayne Roller

    01. Sep, 2012

    The seal issue can send fluid either way, over full transfer case or under filled transfer case. I have had the later on my 97 K1500, transfer case started making a high pitch squeal sound. This one used ATF, so no compatibility issue, but the trany was about a quart high and the xfer was a quart low.

    Just changed the fluid in my 06 Avalanche. It is an automatic case and came with the blue stuff. I used the autotrak II fluid from my GM dealer. BTW, the book recommends a change every 50,000 miles.

  26. joseph

    05. Dec, 2012

    The factory never admits to anything. almost all gm246 transfer cases will eventually develop this leak, it occurs on the tail shaft section were the 5″ internal fingers plate contacts the rattle shims, it will at anytime or any mileage climb above the stainless clips and bang its way through the casing. I have a friend that had this happen at 20,000 miles so long mileage has very little to do with it even though it becomes more common with time. check Youtube, there is an after market cure which completely solves the problem, very simple solution but must be replaced with a precision machined alternative.

  27. Lloyd

    06. Jan, 2013

    Red line oil has replacment oil for Tract II called MT 70w80 GL-4 gear oil is it ok to use and whey do recommend drain plug replace ?

  28. dallas

    18. Mar, 2013

    question you guys are verry help full . i have a 90 c2500 my transfercase today was overfull 2 months ago my automatic trany was overful last weekend transmision wa was low added 11/2 quts fluid today transfer case over full. the pump rub kitt at merchant auto dosent fix this does it ? isthe fluid moving between transfercase & trans going to break somthing i apreciat any advice on this thank you

  29. Al

    11. Aug, 2013

    can GM transfer case fluid “12378396 ” be substituted with Castrol transmax vi?

  30. seiko スポーチュラ

    28. Aug, 2013


  31. Tim

    16. Oct, 2013

    Two posts have talked about Dex VI being the fluid for later trucks transfer cases. That is what the owner’s manual says, but this has been changed.

    GM has a special transfer case and MTF fluid since Dex 3 is essentially obsolete to them. Seems the less viscous Dex VI doesn’t hold up in transfer case applications.

    Synthetic Allison rated TES 295 fluids such as Castrol Transynd are good fluids for manual transfer cases that call for Dex 3 or the later t-cases that called for Dex VI originally. Several companies make TES 295 fluids, even some non certified clones such as Amsoil Torque Drive.

    If you want to run a cheaper conventional fluid in manual cases look for a fluid rated TES 389. Since Dex 3 is obsolete to GM and fluid said to be for “applications previously calling for Dex 3″ may not meet the now obsolete specs. TES 389 is an Allison rating for conventional fluids that used to be called Dex 3.

  32. Justin

    01. Nov, 2013

    So I took my truck in for a loud noise in my transfer case. The dealer said there was a yellow fluid in there (maybe gear oil). I bought the truck new and haven’t changed it yet. Any ideas why it would be yellow not red or blue as recommended?

    2005 GMC 1500 with 60,000 miles

  33. Slammin

    04. Jan, 2014

    I have my transfer case removed at 144,000 miles due to a leak from my tranny front seal. While it is out I am changing the fluid.
    I was also surprised to find about a pint or so of fluid, no real discernible color.
    I notice that my transfer case has the same exact ID as the one shown here. It certainly looks RED. If I follow this thread, this case should take the Auto-Trac II blue fluid, as my dash has the round AUTO 4WD button.
    This is quite confusing.

  34. troy

    10. Jan, 2014

    Gary Conlon
    if you were that overfill u may have the seal between the married t case and trans seal leaking and allowing the trans fluid into the t case. have it checked out

  35. fritz

    10. Feb, 2014

    some people will overfill the t case intentionally. mostly because they don’t want to check it all the time. not too unusual to see an extra quart in there


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