Considering 2015-2018 Denali, best transmission?

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TYF Newbie
Jan 18, 2015
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Sold my 2011 Yukon SLT a few months ago and will be in the market soon for another, so I've been trying to read up on reliability info. I really want the 6.2l engine as a I tow a decent size trailer a few times a year and my old 5.3 seemed to work a little harder than I liked. I will be looking for vehicles with less than 80k. So what is the consensus on most reliable transmission? Seems like 6-speed typically last 150k before they crap out, which is what I got out of my 2011 yukon. 8-speed is a no-go due to shuddering issues correct? Or will a flush with correct fluid make them useable for similar mileage? 10-speed in 2018 holding up for anyone over 100k?

Currently I'm leaning towards paying a little more than I would like for a 2018 to get the 10-speed but is that my best bet?


Mar 4, 2021
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I would 100% go with the 2018+ with the 6.2L and 10 speed. I had a 15 with the 8 speed that made it to 175k and then needed to have a total transmission replacement. I have a friend with a 16 and the 8 speed with over 160k on it now, but he said it's been starting to slowly act up and he did fluid flushes less than every 50k miles. Seems like they are hit or miss and depend on maintenance.

My 10 speed now is at just under 95k miles and has been serviced once. No issues so far and we are original owners of the vehicle. Shifts smoothly. However it seems to like highway driving more, as driving it around my college town on city streets 35mph and less it sometimes gets confused and searches for gears, but I think that comes with having 10 to choose from. The 10 speed is a big noticeable improvement over the 8 speed in many aspects.

Unsure if there are many on here with 10 speeds over 100k miles yet. Since it was introduced in 2018 to these trucks, there are most likely fewer high mileage examples at this point.

Make sure any vehicle you look at has a good maintenance record. Since I've hit 80k miles in January of this year I've had a lot of work done: Front + Rear brake pads and rotors (routine maintenance but my first set of brakes on this vehicle, I still was running factory pads and rotors), front magnetic ride struts (I ordered online and saved about $400 a piece compared to my dealer, still OEM and just had them install them for me with an alignment), water pump and lower oil pan leaking at 92k miles and had both replaced, engine oil cooler lines started to leak badly at 80k miles from extreme cold temperatures in MN, and a couple other things I can't recall off the top of my head. Overall a great truck if you keep up with the maintenance .


Full Access Member
Dec 19, 2015
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I have a 2019 Sub 6.2 10spd and its a great tow vehicle! Tows almost as good as my Ram 2500 Cummins but handles better. With an 8000lb load gets about 10-12mpg and has no problem with hills or trans temps in 110 degree heat in AZ....where the speed limit is 75mph with a trailer. I also recently got a 2015 escalade and was initially hesitant to buy because of the 8speed issues. But when I pulled the build sheet I found it had a 6L90 and not the 8 speed. What a rare bird. I didn't know they mated L86s to 6 speeds. Escalade runs great, does burn outs with 3.42 gears and tows great too. If you can find an Escalade with a 6 speed, you may want to consider it, otherwise go with 2018+. My 6speed gets about 1mpg less than the 10speed when not towing. Towing MPG is about the same.


Supporting Member
Nov 7, 2017
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Stockton, Ca.
6sp or 10sp, 2wd 3.73 if you are looking to tow specifically 5.3 is more economical but the 6.2 has more power.

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