What is the board's thoughts on this engine? Do I have to let it heat up like my diesel truck? Looking at the Sierra Denali/AT4 for my daily driver and road trip truck. My commute is only about 15 mins to work.

DfwAg11 said:

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What is the board's thoughts on this engine? Do I have to let it heat up like my diesel truck? Looking at the Sierra Denali/AT4 for my daily driver and road trip truck. My commute is only about 15 mins to work.

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My dad has it in his silvy and absolutely loves it. Wish I had gone that route in my AT4

Long term ownership reviews generally aren't good. Under 75k miles, you're probably fine. I had one and traded it off because I didn't trust it long term. When it was cooperating, it was a sweet ride. My buddy had one that he ran pretty hard on the highway. He couldn't keep it running after 115k.

GentrysMillTX10 said:

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Long term ownership reviews generally aren't good. Under 75k miles, you're probably fine. I had one and traded it off because I didn't trust it long term. When it was cooperating, it was a sweet ride. My buddy had one that he ran pretty hard on the highway. He couldn't keep it running after 115k.

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A little surprised by this because i'd think it would still be a little early to have a lot of high mileage experience to be able to say this. I've looked some online for long term reliability but haven't found much, what are the long term reviews saying are issues? I have a 2021 3.0 with 75k miles and no issues thus far. Besides the oil belt maintenance at 150k what else do i have to look forward to replacing/fixing?

My buddy had injector, injection pump, computer, wiring, and charging issues. I had def sensor and charging issues in 37k miles. Admittedly we both had 2020 models and I think there was a slight version change/upgrade in 2022 so maybe the newer ones are better

Do y'all heat it up like you had to with the older diesels?

DfwAg11 said:

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Do y'all heat it up like you had to with the older diesels?

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What ambient temperatures are you talking about?

You don't "have to" warm up any engine, both gas and diesel engines have some minor benefit from warming a bit - depending on engine vintage and ambient temperature the "optimal" time can vary. But as I understand it, a modern (last 20 years?) diesel really doesn't need to warm up beyond at most 30 seconds if temps are very cold.

I am not an expert, if my statements sound definitive that doesnt mean I know what I am talking about. But this is my understanding from what I've read over the years.

We had an old diesel truck growing up (early 90s) and my dad had to run it ~15 mins before driving it to work. I always understood that to make a diesel last longer, you never drive it until it the temperature gauge registers a change.

Wife drives a 2021 AT4 with 3.0. We've owned since new.

117k on the clock.

Only issue was something with an injector caused by a wire harness issue. GM knows about the harness issue, fixed it at the factory and fixed ours partially for us. They pulled some BS that the harness was covered, but the issues it caused were not.

Been happy with it so far.

Typically get 22 mpg in real world mixed driving. Best on the clock is 33.9 mpg coming back from Florida (down hill) and actually trying to keep the mpgs up.

They made quite a few changes in '23. I have a '24 and it's been great in the ~30k miles I've had it.

https://www.tiktok.com/t/ZTYsPUNf1/

The general contractor who has done work for us over the years bought one back in October.

500 miles in, a bearing grenades and destroys the engine. To say he's upset is an understatement.

CDUB98 said:

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Can't watch TikTok without the app.

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You most definitely can. I just did. It's a video of a 3.0 Silverado with ~5k miles and a catastrophic failure.

When tried, it just sent me to the app store.

Anyway, this thread is good for me too. I was contemplating buying a new truck with the Duramax.

Sadly in a GMC, they only offer the Duramax or 6.2L. The gas mileage in the 6.2L is atrocious. I want a 5.3L.

Not certain, but i think you can get the Chevy equivalent of an AT4 with the 5.3L. The Trail Boss? But, I like the styling of the GMC more.

Starting to think I'll just hold off another year. I don't need a new truck yet. Just have the itch.

Not an Apple guy and I'm assuming you are, but try this:

https://www.tiktok.com/@noeg123/video/7448698104129309995?

Not an Apple guy either, but your link worked. Thanks.

Weird then. Chrome takes me right to it with no hassle. I Googled your issue and came across this Reddit post. Not sure if it helps if your phone takes you straight to the app store but maybe.

CDUB98 said:

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Anyway, this thread is good for me too. I was contemplating buying a new truck with the Duramax.

Sadly in a GMC, they only offer the Duramax or 6.2L. The gas mileage in the 6.2L is atrocious. I want a 5.3L.

Not certain, but i think you can get the Chevy equivalent of an AT4 with the 5.3L. The Trail Boss? But, I like the styling of the GMC more.

Starting to think I'll just hold off another year. I don't need a new truck yet. Just have the itch.

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A zr2 is closer to an AT4 but it also only available with those engines. A LT trail boss can have a 5.3 and so can Ltz but no trailboss package on a 1500.

Has anyone pulled a travel trailer with the 3.0? How did it perform?

TW78 said:

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Has anyone pulled a travel trailer with the 3.0? How did it perform?

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Watching this one. I'm planning to pull a 28' RV ~1100 miles round trip to Big bend this spring break with my 3.0 sierra

I hope someone on here replies with personal experience, but tons of youtube videos from people towing with the 3.0 duramax if no one here has done it

TW78 said:

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Has anyone pulled a travel trailer with the 3.0? How did it perform?

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I regularly towed a 34' bumper pull with the 3.0. No issues as long as the weight distribution was set up.

These engines have a belt driven oil pump. Both the oil pump belt and the timing chains are accessed from rear of engine with transmission removed.

The belt life is rated at 200,000 miles.

And to be fair, removing a transmission to access the rear timing cover and chains may actually be less work on a modern turbo diesel than from front of engine.

Not a travel trailer but I towed can am side by sides back when I had my 3.0. Power was ok but the truck around it did not handle the weight well. It was a 16 ft trailer with 1 side by side at a time. I made two 4 hour round trips that weekend. I had trailer brakes, that wasn't an issue, but the weight on the truck was issue. The crap z71 rancho shocks probably had something to do with it.

Compared to pulling with an F150, it did not seem as steady and sturdy.

I towed a flatbed trailer with a '72 Chevy Pickup, from east Texas to Travis County. It loved to pull, hills were a breeze, and passing was ease. I know your looking for travel trailer info, so I hope this helps.

Quote:

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The crap z71 rancho shocks probably had something to do with it.

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It's 100% these. I pulled mine and replaced with Bilsteins and it was a night and day difference towing

I appreciate all the replies. I think I will replace shocks or get bags and try my luck. I have gotten as much as 42.6 mpg on a slow 50-55 highway speed (27 mpg average on first 30,000 miles) and I have enjoyed the truck so far. BTW I flew up to Maryland and saved about $14.000 .








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I asked similar questions about a month ago. Some of the responses were helpful. I've been looking at the suburbans and think I'm going to wait until the LZ0 (second gen of the 3.0 diesel engine) comes out in the 2025 models in April or so. My next truck may be the 3.0 duramax AT4. That truck is sweet.

https://texags.com/forums/46/topics/3512155