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View Full Version : 2008 Denali Transmission Fluid and Filter Change


Mr T
06-26-2011, 01:19 AM
Folks:

Took my Yukon Denali to my bro's shop for a DIY transmission fluid and filter change, as well as changing oil in both axles.

I suppose I could do a detailed write-up, although I doubt many would find that very effective.

I do, however, think a few of my lessons learned might be reasonable to share with members of this good board.

1) Note there is no drain plug on the 6L80, so draining and removing the pan WILL BE messy. I managed to splash a significant amount on my head and ht shoulder. At least transmission fluid it doesn't have the vomit-inducing odor that axle grease does.

2) To get the pan out, I needed a cheater bar to slightly lower the left side exhaust pipe 1/2 inch. This facilitated a side rotation of the pan and then it came out with some soft movements back and forth. It does NOT come off easy; don't damage your transmission using force.

3) My gasket has 50K miles and 3 years on it. It was in excellent condition and did NOT need replacing. The OEM gasket is of very high quality.

4) Now that it is out, clean it up dinner-plate clean. I used a solvent to clean it out and then used a degreaser after that. I of course rinsed it a great deal to ensure all that was left was just the pan. While cleaning it, make sure you clean both the pan and tranny surfaces (mounting edges) before you put your cleaned, used gasket, back in place. Some may suggest to always replace this gasket; however, like I said mine only had 50K and was in excellent condition. It didn't leak an ounce.

5) Removing the filter takes a constant down pressure and a side-to-side rocking motion. If the existing filter gasket isn't damaged, I didn't see a logical reason to replace it. I was able to literally "snap" the new filter into the old gasket with a sharp snap sound.

6) When putting the tranny pan mounting screws back in place, don't forget to tighten them in a rotating pattern (going back and forth across the tranny). This helps avoid binding or smashing the gasket too much on any one side. Do all of them by hand first and only tighten by hand till step 7.

7) Make sure you have a torque ratchet to reduce the risk of stripping your transmission's soft aluminum. I read somewhere that 8lb/feet is what the Chevy Sierra's transmission required. I'd like someone--if they have such documents--to confirm what the torque setting should be for the 6L80 transmission that is on the Denali (6.2L). Again, I used 8 which isn't very much force. So I tried to be soft.

8) A full change took 6 quarts; you must use Synthetic Dextron VI. Once you've put at least 5, use the warm/hot instructions to closely monitor how much you are adding. Keep in mind if you over fill, without a drain plug, removing any will be very difficult. Thus, take your time and don't automatically assume you'll need 6 quarts, since your tranny might not have drained out as much. It all depends on how long you leave the pan off. They continue to drip for quite a while.

I hope this helped a bit and I'd love someone to tell me if they have a manual, or similar, that says what the "real" torque setting should be on the mounting bolts.

Zed 71
06-30-2011, 05:01 PM
For others, keep in mind that changing the transmission fluid by dropping the pan, only 60% of the fluid is changed. Around 4 or more quarts are still left in the transmission, lines, and cooler (as applicable).

Hmm, actually 8 ft-lb of torque (96 in-lb) is quite a bit (just from memory) for those aluminum bolts. For my sports coupe it was 35 in-lb (~3 ft-lb) for the aluminum parts. I will confirm when I get home although I have torque specs for the 4L60E.

Zed 71
07-04-2011, 01:38 PM
Per Chilton guide:

4L60E transmission fluid pan bolts 97 in-lbs (8.08 ft-lbs).
6L80 is 80 in-lbs (6.66 ft-lbs)

Are you sure you have the6L80? I thought those came out in 2009.

Mr T
07-07-2011, 11:46 AM
Zed:

How would I confirm which I have?

Per wiki:

http://en.wikipedia.org/wiki/GM_6L80_transmission

But wiki has been wrong before and will continue to have issues :)

---------- Post added at 11:46 AM ---------- Previous post was at 11:42 AM ----------

Wait, I don't know why I'm asking. I'm sure I have the 6L80. When I go into Manual mode I get 6 speeds, not 4.

Zed 71
07-07-2011, 01:47 PM
^ yep if you have the manual mode then you have the 6-speed. Brain fart on my part, the Denalis had the 6 speed before the Tahoes.

2007tahoe
08-01-2011, 02:20 PM
Folks:

3) My gasket has 50K miles and 3 years on it. It was in excellent condition and did NOT need replacing. The OEM gasket is of very high quality.



Thats funny b/c I use alldatadiy most of the time and it stated that the 4l60e trans pan gasket and rearend cover gasket are reusable on my 07. Yea that was not the case. Both of the gaskets were paper gaskets and not rubber. They tore into about 20 pieces.