The GMC Sierra 1500 offers a wide range of engine options tailored to meet a variety of customer needs, but for those seeking the pinnacle of power and capability, the decision often comes down to either the 6.2L V8 L87 or the 3.0L I6 LZ0 turbodiesel Duramax. Each engine brings unique strengths to the table, and the choice largely depends on individual priorities, whether that’s maximum power, or efficiency and torque. The question, then, becomes this – which engine would you prefer in your GMC Sierra?
Let’s start with the naturally aspirated 6.2L V8 L87. Introduced to the GMC Sierra 1500 lineup for the 2019 model year in conjunction with the launch of the all-new fourth-generation pickup, the L87 delivers an impressive 420 horsepower and 460 pound-feet of torque, providing the highest peak power and the second-highest peak torque of the bunch. The L87 is considered to be the second generation of the EcoTec3 engine family, serving as a direct successor to the 6.2L V8 L86.
Highlights include a cast aluminum head and block, with a forged steel crankshaft and forged powder metal connecting rods. The engine has a compression ratio of 11.5:1, a maximum speed of 6,000 rpm and can run on regular fuel, though premium fuel is recommended.
6.2L V8 L87
Paired with the GM 10-speed automatic transmission (RPO code MQB), the L87 is certainly a solid (and popular) option. However, the 3.0L I6 Duramax LZ0 may prove to be the better option for some buyers.
Introduced to the Sierra 1500 lineup for the 2023 model year, the LZ0 Duramax turbodiesel is a direct successor to the 3.0L I6 LM2 turbodiesel offered prior. Output is rated at 305 horsepower and 495 pound-feet of torque, making it an ideal choice for long-distance towing and fuel-conscious buyers. Compared to the LM2, the LZ0 features an updated design with new steel pistons, a returned turbo compressor, new fuel injectors, and improved temperature controls, yielding a 10-percent increase in max power and a 7.6-percent increase in max torque. The LZ0 diesel is also paired with the GM 10-speed automatic transmission.
3.0L I6 LZ0 turbodiesel Duramax
With regard to fuel economy, the EPA rates units of the 2024 GMC Sierra equipped with 4WD and the 6.2L V8 L87 at 15 mpg city, 19 mpg highway, and 16 mpg combined, while units of the 2024 GMC Sierra equipped with 4WD and the 3.0L I6 LZ0 are rated at 23 mpg city, 27 mph highway, and 24 mpg combined.
The question remains – which powerplant would you prefer? Let us know by voting in the poll below!
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“In the 6.2, premium fuel is recommended, not required, but at any detection of knock, add premium fuel immediately” per the ownerns manual. Coworker with a Corvette confirms this and for daily use, runs 87 in the winter, 89 in the summer.
Personally I’d take the 6.2 + performance intake for 435HP 465 tq
I think the L87 is good as well, but it is not without issues. I appreciate the 3.0 I6, but it was NOT AVAILABLE in the Middle East.
Does the I6 have good fuel economy? Sure.
Is it MORE EXPENSIVE than gas? Yes, but depends where you live as well (In Qatar, Diesel costs more than gas- that is why diesel HDs are less common (have seen only one or two Cummins and Powerstrokes seem to be more in use by the police force and by the fire department (civil defence).
If premium fuel that is NEEDED for the 6.2 to run properly (if you do not put it, it can become faulty) is a costly requirement than diesel fuel, then yes, the I6 is a better option. If you want to WORK on the engine- maintenance will be easier for the 6.2 gas than the I6, although compared to engines of yesteryear they are both not as simple to work on …
If the truck is not driven or used much, NEITHER are good options. The “underpowered” 5.3 may be better (yes, lifter issues can happen but occur less than previous generations, and is present in the 6.2, but again as lemons (for both) and a certain percentage-they make thousands or more per month).
The 6.2s have been suffering rod bearing failures as of late, linked to no premium fuel use, bad break in, abuse or lemons (or defective engines prone to fail at some point- indicated by the CSP of MY23s (yes, does not cover MY24s I know, but it may be extended). If anyone knows the percentage of failed 6.2s, total 6.2 numbers, build dates of the ones that have failed (overall), that would be helpful- although info can be confidential).
If anyone has a MY25 that faced this problem, I am curious to hear. I know for a fact that one 2025 Tundra has broken down already (and scores of MY24s have too)…
Please read the comment carefully BEFORE RESPONDING. Thank you.
Per my understanding GM released a TSB on 6.2’s pushrod/lifter issues, and it’s related to oversized lift bores from the factory. All related trucks are getting new engines as it’s a guaranteed failure, but only a percentage of the engines from 2023-24 were affected. Almost all should have been discovered by now.
They should have, but to the users that got lemons it is a BIG inconvenience (two cases here in Qatar), and loaners are not always available. The big issue is that WHEN it happens , you can almost always expect backorder (depending on the situation, if you are lucky, you can get the new engine on time, or else with no loaner, either you use a secondary vehicle which you have( 2nd car in the household) as transport or….not sure what else…).
There is only one failure I know of at 100k miles- vast majority are under warranty. I have heard cases as low as 500 miles to 800 miles in the MY24s.
There are some who have had replacement engines blow as well, but that is more or less owner abuse or shoddy workmanship by the dealer (if you do not have the patience to wait and want to rush things- of course such things can happen). But those cases are not as common…
If there are examples of these MY23-24 6.2s at 200k+ miles, that will show that not all are prone to blowing up….
I think the issue ALSO lies with people that baby them and do not break them properly in, as I said earlier. These engines like to be driven properly, not sit…..
Fuel pump modules cause similar problems, but are not as fatal (as in- they do not kill the engine completely).
I have tried searching for MY25s with similar rod bearing issues and so far have not found YET- only problem is that of an AT4 Ultimate with a check engine light (unsure what the problem was), and some transmission issues in a 25 Denali- not too major, and a 2025 AT4 with a CEL as well.
I hope the MY26s and MY27s (by the end of the generation) get this issue sorted with.
I have a 2020 high country with a 6.2L , 87 octane is all I have used.
No knocks , strong performance.
Good to hear. If you treat the truck with the respect it DESERVES (eg: not abusing it, changing oil every 3k-4k miles with proper oil ), then making it to over one million should not be out of possibility (and no, I am not joking).
Please comment on climate and how often you tow Joey, as that also can be a factor. Interested in a used 6.2, but it will tow a lot. Going up to 89 is fine if I have too.
I really want to like the diesel but they have made it so complicated that I worry it would be a future maintenance nightmare. The 6.2 has almost as much torque but it don’t like it’s need for premium fuel, plus to get that engine GM makes you buy a premium trim package. Faced with these choices I would pick 3/4 ton with a 6.6 gasser, it a better engine and you get many more trim choices with the HD.
6.6 gas is great, but then again its appetite for fuel is a concern. If your concern is DoD, it does not have it. There are already many above 200k-300k miles, so reliability seems to be good so far (aside from some lemons which fail ).
Faced against that, and if you want a base level package, the 5.3 is the only one there. But its power is ……well.
You can get the 6.2 in an RST, but doing so would mean elimination of the bench seat, which is one compromise I do not understand. Plus, at that point you can expect it to be over 200k riyals (50k plus), so it is NOT CHEAP.
I believe the 6.2 WAS available on the Trail-Boss Custom Trim Level. I ALSO saw a 6.2 LTZ model in MY20 for sale which had a bench seat option (very interesting actually)- but like Ms Mary’s foolish decisions, they got rid of such options.
Now the custom TB is ONLY available with a 2.7 I4, a 3.0 I6 or a 5.3 V8. 6.2 engine in that costed around 43k-45k. Pretty good value for a top of the line performance engine, but the terrible management got rid of such an option for the common man…
Those days the RST was around 46k-48k, LT Trail Boss (above 50k plus), both with the 6.2. The Custom TB and the RST served as routes to get the 6.2 at a slightly lower price THAN what you would have to pay for an LTZ or a High Country (or an LT Trail Boss).
Now? The 6.2 is only for the rich.
If towing heavy loads is your priority, the 6.6 gas makes sense (unless long distances, which may mean upgrade to the duramax….which is not really easy to work on).
5.3 is what? It’s a strong motor. Sure it doesn’t make 400HP, but neither did corvettes a couple decades ago.
Also, modern engines behave differently to what fuel is in them. The 5.7 Hemi and 5.0 Coyote are rated on premium fuel, but dynos on 87 show them almost identical to the 5.3. if you must run crap gas and run it hard, the 5.3 might be a great option, as even in the 6.2, running hard on 87 probably will push it to retard spark timing, lowering output.
Also, lower prices of a 5.3 means you can drop a little extra in a CAI or Magnaflow to make up the difference.
I have the 6.2 my best mileage is 9.2/100K up to Whistler and back, Love the truck for towing and in general use. The 6 cylinder diesel has had timing chain problems which means they have to pull the engine out ass the timing is between the engine and trans, why??
I have a Denali 1500 with the LZO and love it. No issues. Pulls our 6000 lb. Boat at 70 with no problem.
Old school here. I will stick with the 454 and 4L80E in my ’93 K3500 or my ’97 K3500 with the 350 and 4L80E. I may get less MPG but aside from the old Allison behind early Duramax trucks GM has not made a HD automatic worth getting since the 4L80E. And I can work on my BBC and SBC in my shop with “normal” tools. Neither truck has ever let me down. The ’97 gets used hard as a chore truck.
If I am going on the trail and camping a lot I will choose a non turbo engine if I will used like I have had my Toyota with 340.000 miles it will be non turbo engine
I can certainly say that the 3.0 is definitely a great engine. I have the previous lm2 that now has 65,000 MI with no issues other than the cooling control valve that needed replacing under warranty. Love the low end power and fuel economy in the 3.0
Get the diesel it’s a no brainer. I’ve had the old version just traded in for a new traverse. That diesel could average 30-32 mpg at 75-80mph. One trip on two lanes gave me 35. It pulls better than the 5.3 and has torque. The new version I’m sure is even better
As much as I would love the 3.0 Diesel, with the oil pump belt located inside the bell housing, and requires replacing at 90k miles. I will not choose. As far as I’m concerned… the big 3 have dropped the ball for years on Hp, fuel economy, and longevity.
Oil pump belt replacement is 200k.
I will be ordering a new GMC Sierra 1500 4X4 crew standard box with the 3.0 Duramax, trailer package, with NHT option to pull a midsized toy hauler. (Just trying to decide on color)
I have a 2018 GMC Canyon 4X4 crew longbox with the 2.8L Duramax. 102,000 miles. I’ve replaced one head light bulb, one tailight bulb, and sensor. That’s it. Thing is a workhorse, reliable, gets great mpg, rides nice, comfortable to sit In. What more could you ask for.
I hope to 3.0 will be as good as it’s little brother has been.