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Thoughts on a GMC 1/2 Ton Diesel needed
Posted on 4/27/25 at 7:23 am
Posted on 4/27/25 at 7:23 am
Whats the OB’s thoughts on these? Have read that they pull a decent amount and get good mpg, but nothing really negative that I can find. Anyone have any personal experience with these engines?
9
Posted on 4/27/25 at 7:50 am to sonoma8
68k miles on one. Just got done with a 47 mile trip and got 27.2 mpg. Only Isai I have had so far is a coolant control valve that went bad and was replaced and that one was bad. I have several buddies that have the same motor and no issues yet one has 150k+ on it.
Posted on 4/27/25 at 8:08 am to sonoma8
I bought a new 2025 AT4 with the 3.0 (LZ0 engine) in February and love the truck. Due for first oil change now. Lifetime average is 23.1 mpg with mix of highway, in town, and towing. It tows very well for a 1/2 ton.
Running Optilube XPD diesel additive mainly for additional lubrication of fuel system components.
Running Optilube XPD diesel additive mainly for additional lubrication of fuel system components.
Posted on 4/27/25 at 8:20 am to sonoma8
I heard they can be deleted now.
Posted on 4/27/25 at 8:30 am to EagleEye99
quote:
Running Optilube XPD diesel additive mainly for additional lubrication of fuel system components.
While it probably doesn't hurt, I think diesel gets lubricity additives at the diesel making place these days. Hpfp failures are not as common as when ULSD first hit the market.
My truck has a CP3 pump which is a great pump but even when I had a CP4 equipped engine, I didn't bother with additives.
From the little bit of failure data I am privy to, the overwhelming vast majority of hpfp failures are due to contaminated fuel, water or DEF damn near every time.
Posted on 4/27/25 at 9:13 am to DownshiftAndFloorIt
quote:
While it probably doesn't hurt, I think diesel gets lubricity additives at the diesel making place these days. Hpfp failures are not as common as when ULSD first hit the market.
My truck has a CP3 pump which is a great pump but even when I had a CP4 equipped engine, I didn't bother with additives.
From the little bit of failure data I am privy to, the overwhelming vast majority of hpfp failures are due to contaminated fuel, water or DEF damn near every time.
Maybe so and by no means arguing, but I like analytical data and information to make a decision. The GM owner's manual specifically calls out the recommended fuel to be "Top Tier Diesel" and it is not sold anywhere that I can find. The manual also states if you can't find it, it is recommended to run an additive in your fuel.
This is the first video that I've found that explains the analytics behind the recommendation. I am not advocating everyone run out and put additive in their vehicle but at least to make an informed decision and do what's best for you
https://www.youtube.com/watch?v=V_iGOXq7DCM
This post was edited on 4/27/25 at 9:19 am
Posted on 4/27/25 at 9:36 am to sonoma8
57k on a 2023 GMC AT4. Couldn’t be happier.
Posted on 4/27/25 at 9:49 am to sonoma8
Just hit 60k on my 2023, more than happy with it. I did have 1 issue, truck was leaking trans fluid from one of the cooler lines. Turned out to be a faulty weld. Manufacturer warranty is 100k drivetrain and 80k for emissions. Which really isn’t a bad deal and peace of mind.
Posted on 4/27/25 at 9:52 am to sonoma8
2021 with 170k miles on it. Transmission went out at 120k miles, that really sucked, being only 20k miles over power train warranty. Other than that no major issues.
Posted on 4/27/25 at 9:58 am to Geauxtac260
Why can none of the companies make a transmission to match engine longevity. It’s across the board…
Posted on 4/27/25 at 10:04 am to Recovered
Same reason we all of a sudden have issues with cams and lifters trashing themselves across all manufacturers. Insane fuel economy standards and the application of tjose standards.
Posted on 4/27/25 at 10:45 am to DownshiftAndFloorIt
I probably need to knock on wood, the Allison on my duramax has been flawless. Pulls a 100hp tractor a couple times a month. I always enjoy reading your automotive post downshift..
Posted on 4/27/25 at 12:47 pm to Recovered
quote:
the Allison on my duramax has been flawless. Pulls a 100hp tractor a couple times a month
Something you'll commonly see is the people who use their trucks as they were designed to be used tend to have fewer issues.
quote:
always enjoy reading your automotive post
Posted on 4/27/25 at 12:49 pm to sonoma8
A Chevy certified mechanic told me they are absolute pieces of shite, just like almost every other truck GM makes now.
This guy drives an older body Chevy truck and a Dodge dually with a 5.9 Cummins and says he'll never get rid of either.
Take that for what's it's worth.
This guy drives an older body Chevy truck and a Dodge dually with a 5.9 Cummins and says he'll never get rid of either.
Take that for what's it's worth.
Posted on 4/28/25 at 12:36 pm to DownshiftAndFloorIt
quote:
My truck has a CP3 pump which is a great pump but even when I had a CP4 equipped engine, I didn't bother with additives. From the little bit of failure data I am privy to, the overwhelming vast majority of hpfp failures are due to contaminated fuel, water or DEF damn near every time.
Mine failed. Caused 12k in damages and new parts. Def was deleted, and the fuel tested perfect, aside from the shards of the cp4 found throughout the fuel system. Gm knows that the cp4 is a ticking time bomb. Why else would they replace it with the older cp3? The lawsuit against them was won, but only in a few states. Those of us that experienced the failure outside of those states just had to eat it.
Posted on 4/28/25 at 3:41 pm to Grnbud
The GM cp4 failures were due to cavitation combined with fuel issues. They didn't have a lift pump and had excessive supply restriction.
The CP3 is a better pump, no question. It's just noisy and big and heavy. None of the stuff the egg heads like to see these days.
The CP3 is a better pump, no question. It's just noisy and big and heavy. None of the stuff the egg heads like to see these days.
Posted on 4/29/25 at 7:59 am to DownshiftAndFloorIt
quote:
use their trucks as they were designed to be used tend to have fewer issues
I bring this up in any "modern diesel" conversations. It's always the trucks that tow once a month and never really get worked. Almost as if they were designed that way.
Posted on 4/29/25 at 10:46 am to sonoma8
I've heard they have bad filter issues if you are just driving short distances every day. My buddy has 1 but he drives all over the state everyday and hasn't complained. I'd go with a 3/4 ton if you want diesel.
Posted on 4/29/25 at 9:07 pm to sonoma8
What is the advantage over gas?
Posted on 4/29/25 at 10:38 pm to DownshiftAndFloorIt
quote:
The GM cp4 failures were due to cavitation combined with fuel issues
You mean the fact that the Bosch (cp4) pump was designed for European diesel and they sold it in the US? Parts sold in a particular country should work with the fuels sold in that country.
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