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Trailblazer (2005 - 2/4WD) transfer case fluid level

Just replaced my transfer case fluid. I ordered 2 quarts because everywhere online I found said it’ll take under 2 quarts before it starts running out of the hole. I used a suction gun to put it in and of course some gets left in the length of the tube. But I figured I’d be fine as otherwise I spilled none and it should take less than 2 quarts anyway. Not the case for me. I put it all in and still was not running out. So I take the end off the gun and tilt it to get what’s in the line in there. I got a little more in but still not “full” and I did spill some so not a full 2 quarts ended up in. Very little was spilled, though.

My question is what is the proper level. Everyone who did a video on changing it says to fill until it runs out and then let it stop dripping before plugging. But one place someone corrected someone saying that and said GM says that when filling it cold (which I was) that it should be a little below the plug. I’m not having luck finding that post again (may’ve been a youtube comment) to see if they mention exactly how far below the plug but I’m between 1/8-1/4". I also can’t find GMs recommendation.

If I’m low, I’ll order another bottle but if the lower level is the correct one, I’ll leave it where it is. Anyone know for sure?

2 quarts should do it. 1/4 below the fill hole is fine.

The only recommended fluid for the transfer case is GM AutoTrak and 2 one liter bottles are used. Also, it is very important to change this fluid every 50K miles.


Not quite 2 quarts went in but if 1/4" below fill hole is good then I should be ok. I did use Auto-Trak II (ACDelco branded, but everything I read says it’s the same as GM branded).

I just bought the car with just under 80k on it and I’m fairly certain it was never done before. Will probably do it again in another 20-30 if it’s still around. It was easy and cheap.

Thanks for the replies.

Another thing- when I put the plugs back in, the fill plug snugged in with no threads exposed but the drain plugged snugged in with 2-3 threads still exposed. I’m hoping the new oil around the fill plug didn’t allow me to over tighten it but if I back off I worry it’s too loose.

I had mine done at 80k and 165k, still looked fresh bud said, he is a gm mehanic that works on the side, At 165k also had front and rear differential fluid change. Is there a way you can stick something, bent straw or whatever to make sure it is near the top? Sure you got the right nuts? For less than $50 I would buy an exta quart and top it off. If you do the differentials I would strongly recommend GM fluid, did not want to mess with adding antislip to the gear oil, comes good from the dealer. is a wealth of information.

I used a bent twist tie to check it and it was 1/4" lower at most.

I was sure I had the right plug in the holes but now I’m second guessing myself. Are they different? I was sure I put them back in correctly because the drain plug fell into the pan and I left it there until I was ready to put it in. But now I’m wondering if I still managed to mix them up.

Thanks for the site link. Looks like a good place to ask some of the TB specifics.

The ACDelco brand was only $6 a quart from Amazon. Actually I just realized they are 1 liter so I should’ve easily gotten 2 quarts in.

If they’re one liter bottles and you put both in, you’re good to go.


The fluid that came out was translucent green. I assume that’s normal. Didn’t smell burnt or anything - no shavings. I didn’t measure it but before I changed it when I checked it, it was 1-1.5" lower than the fill. No signs of any leaking. I have read other posts about them being undefiled from the factory.

I’m only finding one part number for transfer case plug (89059626) and most places list it as a fill plug (others don’t specify) with no mention of also being for drain but they don’t list a separate drain number. Rockauto lists this part number as a drain plug but they have no fill plug listed. So I think they must be the same. I wonder if the case wall thickness is different at these 2 spots where the holes are.

Don’t overthink it too much. 1/4” below the hole or running out of the hole is only 1/4” difference and the transfer case doesn’t care. :stuck_out_tongue_winking_eye:

I always fill differentials until fluid seeps out of the fill hole. My 05 Sierra, I found online that you’re supposed to fill the rear 1/4” (I think, can’t remember for certain) below the hole. I filled it until it seeped out. 1/4” is hard to measure with a bent finger, and I really don’t think those big gears will notice the difference. No issues yet 20k miles later, and I seriously doubt I see any.

As far as the plugs, if they fit the hole, and nothings leaks, you’re good to go.

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