GM 6.6l gas 6 speed vs. 10 speed?

[HntnFsh]

Kicking around selling my 06 Silverado with LBZ Duramax. Been an incredible truck, but considering something with more creature comforts. Mostly looking at 22 and later GMs with 6.6 gas and 10 speed transmission. Wondering if any of you have one and what your general thoughts are? Supposedly the 10 speed gets slightly better fuel economy and is a bit smoother than the earlier 6 speed models.

Sounds like 9 or 10 mpg towing about 8-10 thousand pounds and 14-15 mpg general driving. Sound realistic? Other than possible oil consumption they seem solid. Saw a dandy from out of stat, but was a Canada truck. I guess its probably not a big deal. But it makes me nervous.

[Dan-o]

I also have the '06 LBZ with zero complaints.   

MY brother has had both trucks you describe.   He really likes the 10-speed, for what it's worth.

[fishngamereaper]

Love my 6.6 gasser.
Ive had a dirty max in the past and honestly the new 6.6 gas is just as good.
I have the first gen...its a 6spd. Drove a 10 spd and they are nice. But my 6spd is just fine. My boat is 6k and I've towed equipment up to 15k. Average 10-12 mpg.
Daily driving I'm getting 15. Hwy driving I just got 17 today from Idaho to the WA coast.
And I don't burn any oil... I've heard some stories but it's a non issue for me.

[Bigtine96]

My 6.6 gasser with the 6 speed burned a quart every 3k miles and my 2024 with the 10 speed burns the same. I like the 10 speed but trust the 6 speed more. Had 130,000 miles on the 2020 6 speed and had zero issues. Have 23k on the 24 and no problems either. Both great trucks but the 6 speed has already proven itself.

[NOCK NOCK]

Just purchased a 24, 10-speed, pick it up Saturday. Currently drive an 07 6.0L
I'll let ya know what I think after driving it back from OR. .....Pretty sure all aspects will be nicer than the 07,,,,but it was a Great Truck for me.

[trophyhunt]

I just can't let go of my 06 duramax, man I wish they'd build this same truck again.  I've heard there is a problem with the 10 speed tranny that gmc is well aware of and will pay for the fix if/when you break down, some guys it happened with very low miles, some guys it hasn't been an issue.  I can't stomach buying something that has a known possible problem, my 06 only has about 177,000 on her and with these prices, might just replace everything on the truck and still save 60k.  I thought about the gas motor, but then every time I tow my trailer somewhere, I realize how nice the diesel is.  Good luck with your next truck, you just never know what you're gonna get. 

[300rum]

The 10 speed is worth it, big difference. 

[Happy Gilmore]

10 speed is amazing. Dont ask me to explain why but, we put a lot of miles on trucks and have been through a few dialing it in.

Here's the GM list; all diesel. All bought new except 2003. It had 70k
2002 2500 still have it 340k never had anything replaced
2003 2500 sold at 240 with fuel delivery issues starting
2020 3500 sold at 100k. Friends now have it. Never an issue has 175k now
2024 3500. Have it now, no issues. 55k
2015 3500 less than 3k miles in last 2 years. Everything wrong cant keep it running. Everything front to back replaced stays in limp mode, back to shop tomorrow on a trailer
2024 2500 (because above truck is a pos) has 50k no issues. Being traded in with above lemon at Dave smith for ordered 3500.

2025 3500 and hopefully last truck for a while. Its on a train right now. Will be wife's truck. I take her 2024 as the farm truck/reliable tow rig.

The 10 speeds are sweet and the new platform and package is amazing. The 2015 has been an absolute nightmare.

[HntnFsh]

Thanks for the info. Been leaning towards something with the 10 speed. We will see what comes up! There arent a lot to chose from!

[Woodchuck]

Have the "stacked shift" programmed out of the 10 speed and you will be amazed.

[EnglishSetter]

Not my knowledge base, but was curious.  I've seen some vids were the 10 speed tended to "hunt" a lot.  Don't even remember if it was GM specific.

Found this video specific to the diesel, but should translate to gas.

[spin05]

10 speed is amazing. Dont ask me to explain why but, we put a lot of miles on trucks and have been through a few dialing it in.

Here's the GM list; all diesel. All bought new except 2003. It had 70k
2002 2500 still have it 340k never had anything replaced
2003 2500 sold at 240 with fuel delivery issues starting
2020 3500 sold at 100k. Friends now have it. Never an issue has 175k now
2024 3500. Have it now, no issues. 55k
2015 3500 less than 3k miles in last 2 years. Everything wrong cant keep it running. Everything front to back replaced stays in limp mode, back to shop tomorrow on a trailer
2024 2500 (because above truck is a pos) has 50k no issues. Being traded in with above lemon at Dave smith for ordered 3500.

2025 3500 and hopefully last truck for a while. Its on a train right now. Will be wife's truck. I take her 2024 as the farm truck/reliable tow rig.

The 10 speeds are sweet and the new platform and package is amazing. The 2015 has been an absolute nightmare.

I got a 2025 3500 GMC AT4 in may.  Its been great.  Lot to learn of this new fancy stuff coming off a 04 3500 Ram.  But yea the 10 spd is so far awsome. in tow haul with the camper i barely have to ever touch the brakes.

[trophyhunt]

Has anyone else heard about the problem with the 10 speed?  GMC supposedly has a fix but they fix it after it breaks.

[Tim in Wa.]

from what I've heard the problem has been with 1500s not 2500 0r 3500

[Bigtine96]

Has anyone else heard about the problem with the 10 speed?  GMC supposedly has a fix but they fix it after it breaks.

Yes the 10 speeds have been known to have valve body issues, mine started shifted a little strange one day was told there was a update to the tranny software but when I went into Chevy they said all was well and nothing they can do. So yeah it will be a once it fails type of situation. Typical

And no not just the 1500’s have issues.

[HntnFsh]

Been seeing some nice 2024s popping up set up up for goosenecks with 35 or 40000 miles. Obviously commercial use vehicles. Tempting to buy a nice used one, but also not tempting because its most likely pulled heavy its whole life. Wondering if they are trading them in for new 6.6 gassers or going back to diesels?

[trophyhunt]

Has anyone else heard about the problem with the 10 speed?  GMC supposedly has a fix but they fix it after it breaks.

Yes the 10 speeds have been known to have valve body issues, mine started shifted a little strange one day was told there was a update to the tranny software but when I went into Chevy they said all was well and nothing they can do. So yeah it will be a once it fails type of situation. Typical

And no not just the 1500’s have issues.

Do you also have low miles? 

[Bigtine96]

Has anyone else heard about the problem with the 10 speed?  GMC supposedly has a fix but they fix it after it breaks.

Yes the 10 speeds have been known to have valve body issues, mine started shifted a little strange one day was told there was a update to the tranny software but when I went into Chevy they said all was well and nothing they can do. So yeah it will be a once it fails type of situation. Typical

And no not just the 1500’s have issues.

Do you also have low miles?

26,000 miles as of this morning.

[trophyhunt]

Has anyone else heard about the problem with the 10 speed?  GMC supposedly has a fix but they fix it after it breaks.

Yes the 10 speeds have been known to have valve body issues, mine started shifted a little strange one day was told there was a update to the tranny software but when I went into Chevy they said all was well and nothing they can do. So yeah it will be a once it fails type of situation. Typical

And no not just the 1500’s have issues.

Do you also have low miles?

26,000 miles as of this morning.

That sucks!!!! 

[spin05]

Has anyone else heard about the problem with the 10 speed?  GMC supposedly has a fix but they fix it after it breaks.

Yes i am aware of it. Like others have said its a valve body issue. I will be changing fluid often, Suppose to be fixed in the 2025 model but will see.  The fix it to install this or his entire valve body.   https://nextgendiesel.com/products/project-carbon%C2%AE-10l80-e-diy-valve-body-upgrade-kit-v3-1?srsltid=AfmBOoqWuGQu82rIqOOIUJFi08VwXktIBxnvT6gH06u1RgLP86_T5CMe&variant=44893280075949       Which of course voids your warranty

[Happy Gilmore]

Have had 3 10 speeds, one 6 and 2 5speeds.

Only had an issue with the 5 speed. Bought the truck chipped and modified. It was terrible. Dont do that to a truck unless you plan on selling it and not putting a lot of miles on it or you dont tow much and just drive to the mall.

[NOCK NOCK]

Im gonna fess up......what is the purpose of a 10 speed tranny?  I'm a pretty basic guy, 2wd-4Hi-4L, gets me anywhere pulling anything. 
What is the use for 10 speeds/gears in a truck?

With that being said, I do love the truck, lots of power and drives like a caddy, although it is quite larger than my 07 in height & width. What's crazy is that it has the 6-10 (medium) bed......yet truck is the same length as my 07 crew long box.

[Boss .300 winmag]

Im gonna fess up......what is the purpose of a 10 speed tranny?  I'm a pretty basic guy, 2wd-4Hi-4L, gets me anywhere pulling anything. 
What is the use for 10 speeds/gears in a truck?

With that being said, I do love the truck, lots of power and drives like a caddy, although it is quite larger than my 07 in height & width. What's crazy is that it has the 6-10 (medium) bed......yet truck is the same length as my 07 crew long box.

The standard max width is 8.5’, how wide was the 07?

[NOCK NOCK]

Honestly have not measured, just parked them sxs. The 24 (prolly the boxy hood/front end) makes the 07 (more sloped down/aerodynamic front end) look tiny. Length is very close to same....24 has 6'10" bed, but much more space in the back seats compared to the  07

[Happy Gilmore]

Honestly have not measured, just parked them sxs. The 24 (prolly the boxy hood/front end) makes the 07 (more sloped down/aerodynamic front end) look tiny. Length is very close to same....24 has 6'10" bed, but much more space in the back seats compared to the  07

I miss the fold flat back seats. New trucks fold up seats arent much help.

[HntnFsh]

10 speed is amazing. Dont ask me to explain why but, we put a lot of miles on trucks and have been through a few dialing it in.

Here's the GM list; all diesel. All bought new except 2003. It had 70k
2002 2500 still have it 340k never had anything replaced
2003 2500 sold at 240 with fuel delivery issues starting
2020 3500 sold at 100k. Friends now have it. Never an issue has 175k now
2024 3500. Have it now, no issues. 55k
2015 3500 less than 3k miles in last 2 years. Everything wrong cant keep it running. Everything front to back replaced stays in limp mode, back to shop tomorrow on a trailer
2024 2500 (because above truck is a pos) has 50k no issues. Being traded in with above lemon at Dave smith for ordered 3500.

2025 3500 and hopefully last truck for a while. Its on a train right now. Will be wife's truck. I take her 2024 as the farm truck/reliable tow rig.

The 10 speeds are sweet and the new platform and package is amazing. The 2015 has been an absolute nightmare.

Were these all diesels?

[HntnFsh]

I would love to find a lot that has a nice used 6.6l gasser with the 10 speed that would let me hook my trailer to it for a short tow test!

[Happy Gilmore]

Yes, all diesels. 2015 3500 with 165k been at Demaris GMC missoula after Windy Chevrolet in Ellensburg and Mccurley in Pasco. Now playing blame game on who damaged the wiring harness but, want me to pay for it. They all just pull parts and replace it hoping to be a mechanic.

[Happy Gilmore]

I would love to find a lot that has a nice used 6.6l gasser with the 10 speed that would let me hook my trailer to it for a short tow test!

The gassers are fine if you feel good spinning them at 5,000 rpm up all the hills. They like to rev. It creeps me out.

[HntnFsh]

  Thats what scares me to. I havent run a GM gasser like this, but have run Fords at work. Not a fan of how they rev when pulling. Always puts me on edge hearing an engine whine like that when pulling a load. But it seems like these 6.6l gassers are built for it. Maybe I could adapt!

[Happy Gilmore]

  Thats what scares me to. I havent run a GM gasser like this, but have run Fords at work. Not a fan of how they rev when pulling. Always puts me on edge hearing an engine whine like that when pulling a load. But it seems like these 6.6l gassers are built for it. Maybe I could adapt!

Used to have a fleet of various model trucks when I was a PM/estimator/construction. The GM 8.1L was the only old torque monster. A friend of mine got a 7.3 gasser Ford and loves it. I haven't driven one yet. I had a half ton 6.2L Chevy i got when my f 350 was stolen right before covid and it was a beast. Towed our artic fox trailer fine but the suspension was way too light for it. I made two trips hauling stuff home from California. I sold it during the covid crisis after using it to tow my car trailer back and forth from fall city yo montana when I moved here. Put 70k on it that year almost all towing. It was a great truck and still my favorite pick up ive ever owned.

[Boss .300 winmag]

So the 6.6 10 speed gasser just came out in 2024?

[HntnFsh]

2020

[fishngamereaper]

So the 6.6 10 speed gasser just came out in 2024?

With the ten speed yes.
The previous year's have the 6.