Need some help I stopped by the GM dealership to get the right gear and transfer case oil for my 07 Hummer. I gave him the VIN # it took him sometime to look it up and then called someone over to help him. I want to make sure these are the correct oil for my 07 These are what he gave me. He said I needed 5qts of the gear oil and I know the transfer case takes 1.6qts

Dexron VI 88865601
75W-90 GL-5 88900401

He also handed me a print out that shows a different part number 89021677 for the gear oil. I didn't noticed that until I left I didn't buy anything yet I told him I'll look into it and get back to him.

Any help would be great I don't want to install the wrong oil. Thanks

 

You certainly do not need to spend your first born child at the dealership to get fluids for any H3. I use Mobil 1 in the correct weight for Motor, Diffs, T Case & Auto Trans. But them where you find them on sale at the best price.

The Owner's Manual for the 2007 says to use Manual Transmission Fluid for the T Case, depending upon the year it also says AT Trans Fluid. The T Cases are basically all the same so either is fine, I would not loose any sleep over MT vs AT fluid.

More important is to be aware that depending upon your Vin# you may have to add a small amount of fluid to the T Case after full through the speed sensor hole as the early BW T Cases had the fill hole too low to get the level where GM Engineers wanted it. See below from an old Draketh post:

Transfer Case....MAKE SURE TO READ THIS CAREFULLY FOR CORRECT FILL LEVEL and RECOMMENDED FLUID. THERE ARE DIFFERENT FILL LEVELS AND DIFFERENT FLUIDS
Approximate capacities (see below) 1.5 liters/1.6 quarts

Again, recommended to raise or make sure vehicle is level.
Remove the drain plug and allow the t/case to drain.
After draining fluid, install pipe sealant to the drain plug and torque to 18 lb ft or 25 N.m.
Remove the t/case fill plug, and fill to bottom of fill plug hole:
2006 and 2007 Model Year Vehicles use manual transmission and transfer case fluid
2008+ Model Year Vehicles use Dexron VI trans fluid.

Apply pipe sealant to fill plug and torque to 18 lb ft or 25 N.m.
NOW, for all 2006 Model Year Vehicles and for 2007 model year vehicles if the VIN is 56TDN13E778100102 or prior:
Remove the speed sensor connector (top rear of t/case), then remove the speed sensor.
Add 250 ml (8.45 oz) of manual transmission and transfer case fluid through the speed sensor hole.
Install the speed sensor and tighten to 13 lb ft or 17 N·m. Then install the speed sensor connector to the speed sensor.
This additional fluid is needed.

Adding fluid into the speed sensor hole is not required for 2007 vehicles built after 56TDN13E778100102 or 2008 vehicles.

 

Thanks for the reply. I did my first oil change using 5W-30 Mobil 1 with ACDELCO filter. My 07 has the later transfer case so I don't need to fill from the speed sensor. I only went to the GM dealer to get the right oil because I was getting confused which oil to get, now after going I'm more confused.

It looks like I can use Mobil 1 75W-90 SYN gear lube for both front & rear differentials

Mobil 1 site doesn't list anything for the transfer case but Rockauto shows to use VALVOLINE811095Synchromesh Manual Transmission Fluid.

 

Mine also has the rear locker, not sure it that matters or not?

 

So it looks like the gear oil listed on the paper he handed me for my 07 GM part# 89021677 was replaced by GM Part # 88900401 so I think I'll go with that but I'm still not sure what to use for the transfer case just yet.

 

Actually, my manual for my early 2007 H3 has a totally different page for fluids lol!
Kidding aside I went with the Dex VI but then after further research drained it and purchased the exact ACDel GM product listed. It was visually different right out the jug. The thickness and smell were also different. Its been awhile so I don't remember all the stuff that encouraged me to swap to it but I'm glad I did.

 

If I remember correctly it was because it went with a manual trans reference and specs. I think.

 

T Case = Synthetic AT Trans Fluid or whatever MT Trans Fluid you want. It is not called Transfer Case Fluid because they use Transmission Fluid (your choice AT or MT). Or.... any other synthetic AT Trans Fluid compatible w/ Dexron-VI. Doesn't matter, flip a coin. That way whatever you do not put in the T Case, can go in the Auto Trans if you need it later.

I think mine has Valvoline Full Synthetic Dex-VI ATF in it, but I can't remember for sure as it don't matter.

 

My issue has been resolved. I went back this morning to GM to pick up the gear oil. A different guy was at the counter I handed him the invoice from yesterday to get the gear oil, I also wrote the old part number for the manual/transfer case oil 88861800 that my owner's manual calls for, I told him about yesterday the other guy was telling me to use Dexron VI and he said yes, I was the other guy that helped him look it up and that's what GM calls for your 07 H3. I told him there is a service bulletin saying if your owner's manual calls for manual/transfer case oil 88861800 do not use Dexon VI he said no you can use it but once its in there you can't go back to the old stuff.

I kept pushing the issue with him and I said I know manual/transfer case oil 88861800 is not available and he said no we still have that but it for manual H3 only I said no it's also for the transfer case and showed him a picture of my owner's manual that states to only use that. He went back to get my two bottles and came back and said you are right it does say manual/transfer case.

It pays to do your research. Hope this helps others

From my owner's manual



The correct transfer case oil.

 

What was the issue with "it doesn't matter use AT or MT Fluid?"