Looking to trade in the 2019 5.3 for a 2025 ZR2 with either the 3.0 Duramax or the 6.2 V8 gasser.

The Duramax is the updated LZ0 from the previous version LM2. Of course it has all of the emissions BS. The oil pump belt is now on a 200,000 mile interval.

The 6.2L is on the other side of the major recall with presumably manufacturing updates to prevent the failures they've seen.

My use case is daily driving to and from work approximately 35 miles on the highway each way for a total of 70 miles per day. The weekends would be mostly city driving. It would be used to haul mulch/landscape materials a few times a year, dog kennels sporadically. There would be very little towing. My current truck is the 5.3 with a 6" lift and 35's currently getting about 14.2 mpg.

I'm torn between the two engines. Help me out!

I'd say get the diesel but in the long run, the 6.2 is probably cheaper. Here's what Grok had to say for a cost benefit analysis of the two.

https://grok.com/share/c2hhcmQtMw%3D%3D_83d8a4d2-9c56-4539-9c0d-214b62d0b830

6.2 will work if you use 0w40.

Yeah the 2025's have supposedly solved the manufacturing defects and are still recommending 0W-20. I can believe that but part of me thinks it's possible that GM is claiming the 2025's are good so EPA doesn't ask them to recertify the mileage reduction due to higher viscosity oil.

I didn't choose to drive a truck to get good gas mileage. 6.2L rips

Grok analysis said initial purchase cost with diesel was higher, but that was comparing to 5.3. At least with Tahoe/Suburban if you get diesel over 6.2 gas the MSRP is about $900 less

The resale value is probably higher on the 3.0. Overall it looks like kind of a toss-up financially. I would probably go diesel just for the sake of doing it.

6.2L if it's not affected by recall. Then rip out the ****ty DFM system, drop in a truck boost cam with good lifters/pushrods, then install a whipple and get a good tune. After all this is a ZR2.

That is also tempting. Definitely drive both and see which one you prefer.

Whatever engine you decide, make sure you LS swap it

3.0.

I'd love one in a zr2 but I rarely see them

sts7049 said:

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get the big v8 while you still can. who cares about mileage

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I care about it not falling apart

Diesel should last longer than the gasser.

Green2Maroon said:

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Diesel should last longer than the gasser.

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That's up for debate with modern diesels. Most people tap out at 100-150K anyway and any modern gas or diesel engine will easily make it to that assuming routine maintenance is completed.

Is it all the emissions stuff that makes modern diesel engines worse for longevity? The metallurgy and build quality is surely excellent these days on the actual engine.

Green2Maroon said:

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Is it all the emissions stuff that makes modern diesel engines worse for longevity? The metallurgy and build quality is surely excellent these days on the actual engine.

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Yes that and crappy fuel pumps that explode and shoot metal shavings throughout your fuel system. Low Sulfur Diesel likely contributes.

They're just very complex even if the engine internals are bulletproof and live life at lower rpms than gas equivalents.

Green2Maroon said:

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Is it all the emissions stuff that makes modern diesel engines worse for longevity? The metallurgy and build quality is surely excellent these days on the actual engine.

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Yes, diesels create a lot of soot and all the emissions stuff recirculates that soot back into the engine. Over time the soot clogs things up and creates issues. Diesel fuel itself is also dirty in general and people are bad about changing fuel filters on time which leads to lots of issues, especiallywith the newer Bosch pumps. Then you have DEF to deal with and also Diesel fuel gels up in low temps so if you live in North Texas or higher lattitude, you have to add anti-gel fuel additive in the winter time or use an engine block heater.

I like diesels but there is no denying that they are more of a headache maintenance wise and more expensive overall.

I used to work for a small company selling automotive fluids. We sold oceans of DEF. It was insane.