Thoughts on purchasing a higher-mileage Duramax?

[carguy79]

Curious to ask those in the forum who have bought recent model, higher-mileage Duramax vehicles. I am exploring purchasing a year-old Denali Ultimate (with Super Cruise) that has just over 60k miles; service records show religious maintenance, oil changes, fuel filter changes, no accidents, etc. My plan is to not to use as a daily driver, but rather for occasional longer road trips and towing a camper.

Any used vehicle comes with risk, of course, so I am not expecting it to be as new. For those who have bought with higher mileage Duramax of this generation, what types of issues should I potentially plan for? Any Duramax-specific maintenance items to be aware of with higher-mileage engines based on your experience? Other things I should consider?

 

[Stbentoak]

60K Miles is nothing on a diesel engine. I would have all the fluids changed on the vehicle as part of a prerequisite to buy. If everything else adds up and it is in good shape and a fair price, I wouldn't let that mileage stop me and all.

 

[blackelky]

If only we could find a way to legally delete the smog lol

 

[ReaperHWK]

60k high mileage? lol. That diesel is barely broken in.

 

[Marky Dissod]

Any halfway decent turbodiesel that fails to exceed 300,000 miles is an indictment of its previous operators.

... service records show religious maintenance, oil changes, fuel filter changes, no accidents, etc.

If the motor oil was changed every 5000 miles, good. If more often than that, so much the better.
If you address maintenance items slightly sooner than recommended, 300,000 miles should be easy.

 

[Big Bad Allis]

I year old with 60K miles is better than 3 years old with 60K miles. The miles will be mostly highway miles and not a lot of short operating trips. With the good service records, I would not hesitate one bit.

 

[dbphillips]

If it's a 3.0L and it wasn't a case of the owner dying and no one in the family wanting it, I wouldn't go near it. I was willing to let GM buy mine back as a lemon due to time out of service (turns out it didn't qualify), but the only way I'd sell it is if it had a known issue, even though I haven't been able to confirm the fix for oil loss.

 

[TiGrayMSM]

My take as fellow 3.0 owner (2022 Yukon XL) is to buy the newest model year you can, especially for the LM2 diesels (2021-2024 for the SUVs). The early LM2s do have issues, which I have confirmed after befriending the diesel mechanic at our dealership. Areas to look out for per the tech:

1. Early builds (2020-2021) are prone to oil leaks (rear main)
2. Early build LM2s are starting to come in for timing issues caused by timing chain stretch. This is a massive cab-off job. The tech said GM updated the chains with a new design in 2022 (maybe earlier?)
3. Oil consumption (there is a TSB for this, involves replacing the camshaft housing. Also early builds)
4. Coolant control valve. He has seen both LM2 and LZ0s coming in with this issue, but especially higher mileage LM2.

Per the technician, almost everything involving the LM2s is very labor intensive so he is wary of owning one outside warranty.

With about 70k on our 2022 now, this is what has been replaced that is diesel specific: All replaced under warranty (some of it covered by CPO warranty):

1. NOx sensor
2. DEF sensor recalibration (the gauge was wildly inaccurate when towing. The update has helped somewhat)
3. Oil consumption (heavy consumption for us when towing). We had the oil consumption TSB performed and so far results are excellent. But FYI, this job was billed at 18 hours!
4. EGR valve replacement and EGR cooler replacement due to coolant leaks.
5. Coolant control valve replacement (P1098)
6. Intercooler replacement (massive internal coolant leak)

On the plus side, doing a transmission fluid/filter change is much easier on the diesels. The gassers have a crossover pipe right under the pan. I was intending to keep the Yukon long term.... as we do for all our cars. However, in this case, I will make the decision when we are closer to 100k.