2024 Silverado 2500 HD with the 6.6 Gas (L8T) Engine

dbart · October 2, 2023

I am one of the ones that went from Diesel back to Gas...

First diesel was a 2004.5 Silverado with the LLY Duramax. Had no issues with that just wished at that time it had the 6spd Allison instead of the 5spd. 2018 I sold it and bought a new 2018 L5P Duramax SLT/Z71 CC. Had a ton of issues with it but it towed great and over the life of it at 84K miles averaged 16.7 mpg. Straight freeway driving was 18-20, to work and back was 16-19, around town about 14.

That truck got lemon lawed and when all said and done, I ordered a 2024 GMC 2500 AT4 with the 6.6 Gas. I was tired of the emissions crap, the cost of diesel, the fuel filters, DEF and just all the electronics required to run the new Diesels.

I have 5,000 miles on my new truck, and I love it. It tows just as well as my diesel, but I do miss one thing...the Exhaust brake.

I just did 965-mile round trip towing my Can Am in my 16' box trailer to Utah and back and I averaged 9 mpg, but my buddy's I was following all wanted to do 85-90 mph! UGH!

Had I stayed where I like to tow....65, I would have been in the 10's for sure. That trip in my Duramax probably would have been 12-13.

So far in the gasser, freeway driving can see 19 mpg, but it is usually around 17-18 at 65-70 mph.

To work and back 15-18, around town about 12-14.

I simplified my life going with the gas version, but I do miss the diesel just a little bit...only for knowing I could tow whatever I wanted pretty much. Now having said that, I won't ever get a trailer that is that heavy...so for me going gas just made sense and I love it.

~Dale

October 2, 2023

1 hour ago, dbart said:

I am one of the ones that went from Diesel back to Gas...

First diesel was a 2004.5 Silverado with the LLY Duramax. Had no issues with that just wished at that time it had the 6spd Allison instead of the 5spd. 2018 I sold it and bought a new 2018 L5P Duramax SLT/Z71 CC. Had a ton of issues with it but it towed great and over the life of it at 84K miles averaged 16.7 mpg. Straight freeway driving was 18-20, to work and back was 16-19, around town about 14.

That truck got lemon lawed and when all said and done, I ordered a 2024 GMC 2500 AT4 with the 6.6 Gas. I was tired of the emissions crap, the cost of diesel, the fuel filters, DEF and just all the electronics required to run the new Diesels.

I have 5,000 miles on my new truck, and I love it. It tows just as well as my diesel, but I do miss one thing...the Exhaust brake.

I just did 965-mile round trip towing my Can Am in my 16' box trailer to Utah and back and I averaged 9 mpg, but my buddy's I was following all wanted to do 85-90 mph! UGH!

Had I stayed where I like to tow....65, I would have been in the 10's for sure. That trip in my Duramax probably would have been 12-13.

So far in the gasser, freeway driving can see 19 mpg, but it is usually around 17-18 at 65-70 mph.

To work and back 15-18, around town about 12-14.

I simplified my life going with the gas version, but I do miss the diesel just a little bit...only for knowing I could tow whatever I wanted pretty much. Now having said that, I won't ever get a trailer that is that heavy...so for me going gas just made sense and I love it.

~Dale

Solid information and beautiful truck.

I had a 2015.5 Denali Duramax and mostly loved it. My recreational trailer is only 5500 LBs which is like not towing at all. I pulled some 10-12k stone trailers and it still hardly taxed that motor.

Moved into a different need with less payload required for work. Bought a 2020 6.2L 1/2 ton. Pulling the same rec trailer fully loaded with family, generator, paddleboards, etc, I have averaged over 10 MPG in 4 years of use. I can go up the Eisenhower at 75 MPG and any other pass if I really push it. Without a trailer, I average 18 in mixed driving, and when needed, it is plenty quick to 60. I have nothing but high praise for it, and if you can live with the 1360 LB payload, it is a jack of all trades.

My needs will change early next year and again require the capacity to put 2500 LBs in the box. So I am likely to go back to a heavy duty, but really have no need for the diesel. My 2015.5 had the normal sensor issues and DEF tank replacement, and thankfully all were fixed under warranty. The gasser with 10 speed should suit me fine. Of course I will miss the added grunt of the diesel, the sound of that motor, and as you mention, the exhaust brake. My 6.2L 1/2 ton uses engine braking surprisingly well, and I hope the 6.6L HD will be reasonable.

rjgvt · October 3, 2023

7 hours ago, dbart said:

I am one of the ones that went from Diesel back to Gas...

First diesel was a 2004.5 Silverado with the LLY Duramax. Had no issues with that just wished at that time it had the 6spd Allison instead of the 5spd. 2018 I sold it and bought a new 2018 L5P Duramax SLT/Z71 CC. Had a ton of issues with it but it towed great and over the life of it at 84K miles averaged 16.7 mpg. Straight freeway driving was 18-20, to work and back was 16-19, around town about 14.

That truck got lemon lawed and when all said and done, I ordered a 2024 GMC 2500 AT4 with the 6.6 Gas. I was tired of the emissions crap, the cost of diesel, the fuel filters, DEF and just all the electronics required to run the new Diesels.

I have 5,000 miles on my new truck, and I love it. It tows just as well as my diesel, but I do miss one thing...the Exhaust brake.

I just did 965-mile round trip towing my Can Am in my 16' box trailer to Utah and back and I averaged 9 mpg, but my buddy's I was following all wanted to do 85-90 mph! UGH!

Had I stayed where I like to tow....65, I would have been in the 10's for sure. That trip in my Duramax probably would have been 12-13.

So far in the gasser, freeway driving can see 19 mpg, but it is usually around 17-18 at 65-70 mph.

To work and back 15-18, around town about 12-14.

I simplified my life going with the gas version, but I do miss the diesel just a little bit...only for knowing I could tow whatever I wanted pretty much. Now having said that, I won't ever get a trailer that is that heavy...so for me going gas just made sense and I love it.

~Dale

Great write up and nice truck! I’d like to get a 24 AT HD in February or March. Currently have a 2018 GMC 1500 DC 6.5’ box but want an HD gasser, no cylinder deactivation or start/stop. Don’t need an HD but like them.

Going to call the dealer tomorrow to get an order started if my sales guy is in. Need to get through hunting season then will have time to get an ARE cap ordered and installed.

How do like the running boards? I’m on the fence between those or the wider ones that sit a couple of inches lower. Yours are definitely slick looking.

Handy · November 8, 2023

I received my 2024 2500HD 6.6 gas in July and just did my first oil change at 2290 today with zero oil consumption. I love this gas engine after having the Duramax in 3 trucks since 2001. The 10-speed trans is amazing and I love it also. I just drove 600 miles last weekend, freeway miles, and averaged 15 mpg. I towed a 10,000 pound trailer about a month ago for about 160 mountain and desert miles and got 7 mpg.

John Mc1975 · December 19, 2023

I have a 2020 2500HD 6.6 gas with 78000 miles. The truck does consume a few quarts between changes. I just added 3 qts with about 22% oil life. Also make sure techs are completely tightening the filter, it is in a tight spot and I had loose filters twice in the last 3 yrs.

9thShodan · December 25, 2023

I had a 22 3500 Denali dually gas and put 41000 miles on it. Changed the oil every 5k and it was always on the money. Never burned a drop. I traded that in in March for the 24 Denali 3500 dually gas and just did the 3rd oil change and didn't burn a drop. It's always right on the line. Great truck, I hear people complain about things but I've never had an issue and I tow over 20k up the mountains in VA regularly.