2021 Tahoe LT Duramax 4WD at 1,100 Miles.

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CTown Duramax

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At 1,100 miles in three and a half weeks of ownership. 2021 LT Duramax 4WD (black/black, 18" wheels, single speed transfer case).

Having a full-frame chassis and a modern turbodiesel feels like the way to go.

The engine has more than enough power for every situation. It is probably a little slower 0-60 than the 327ci V8, but it seems to make up for that IMHO with its instant low-rpm torque for roll on performance from a start and 60-80mph. 10-speed auto transmission seems like a big advancement regardless of engine.

My milage figures come from the dashboard read out, leaving trip one untouched and resetting trip two. The mpg meter was the same as dividing odometer miles by gallons at the pump when I checked it that way.

On our single highway trip so far, hilly terrain, we got 29.7 mpg over 165 miles with a light foot going 70+/-mph. Driving in the usual regional style on the return 80+/- mph got 26.4 mph.

80% of our 54 engine hours have been in heavy traffic dropping off or picking up the kids from school in another part of the city at rush hour. A mile can take half an hour. Our 1,100 mile average is 21.3 mpg. I am not using auto stop. All this is the same mpg +0.1 we got from our Impala V6, a fast, efficient sedan that must have had much better aerodynamics.

I decided to get a diesel after renting an Audi A6 TD40 in Germany. Diesels have come a long, long way from the old M-B 240D. I enjoy the diesel sound. There are reviews saying you can't tell it's a diesel. Not true, but it has good manners. It doesn't smell like a diesel at all, thanks to the blue tech DEF system (whether I want it or not). My opinion of performance is subjective, but this engine never breaks a sweat. It is smooth in every situation. Power is always more than enough to move this huge car smartly. I am surprised at the high 5,100 rpm redline and how the diesel still pulls at higher rpms.

The Tahoe is worth the trouble and expense. It is comfortable over the road. It handles very well. The luxury-appointed interior (even an LT like mine) makes traffic jams easy. My ideal car would have been the last model Caprice wagon with the 3.0 L Duramax turbo diesel. Now that I am getting used to piloting the automotive equivalent of an Iowa-class battleship through Colonial-era streets, I love it.

PS - If anybody knows, is the 3.0L Duramax LM2 related to the Benz straight six 3.0 liter turbodiesels in the S 350d? The output statistics are the same after converting units, including lbft to Nm and hp to PS.
 
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TrueAt1stLight

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That’s a great write-up! Thanks for sharing. One damning thing going for the (late) German luxury diesels is their inability to run any biodiesel blend at or greater than 10%. I had 3 BMW X5’s in a row that were toast before 50k miles running them on MN’s super-high blend biodiesel. Thankfully your Duramax is engineered to drink B20, and like a sir!
 

Geotrash

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Thanks for the write-up. I'm tracking people's experience with this engine with the intent of buying one in the next few years. To your question, no, it is a clean sheet design from GM. Though there was an engineering paper written several years ago that showed that .5L/cyl is optimal, so lots of engines now we will see have multiples of that figure for their displacement.
 

Seamus

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This 3.0 sells me everyday i drive it. I love it more and more and it does it all well. Tows fantastic, and the mileage after break in is crazy good. Love this motor. True it pulls away great and very peppy around town. The 6.2 is if you love passing cars quickly, but this thing moves along really well. Great motor.
 

Decreed_it

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+1 to the Baby Duramax love. The only one we considered.
Now that I am getting used to piloting the automotive equivalent of an Iowa-class battleship through Colonial-era streets
Real recognize real! just described driving ours as piloting a large boat in another thread LOL
 

Echoboy

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This 3.0 sells me everyday i drive it. I love it more and more and it does it all well. Tows fantastic, and the mileage after break in is crazy good. Love this motor. True it pulls away great and very peppy around town. The 6.2 is if you love passing cars quickly, but this thing moves along really well. Great motor.
I have the 2021 4x4 suburban RST with 3.0 diesel. Have 12K miles and 3 oil changes on it and everything about it is GREAT !! Great around town, trips, and pulling my 7,000 lb cargo trailer.
A concern I have is that every other diesel I've owned [ for 16 yrs ] needed a fuel additive to keep the engine , etc. clean and lubricated. Every service tech that I've asked about this stammered around with a different answer, like they weren't sure ...?? does anyone here have advice for this ??
 

sqd pkl

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I have the 2021 4x4 suburban RST with 3.0 diesel. Have 12K miles and 3 oil changes on it and everything about it is GREAT !! Great around town, trips, and pulling my 7,000 lb cargo trailer.
A concern I have is that every other diesel I've owned [ for 16 yrs ] needed a fuel additive to keep the engine , etc. clean and lubricated. Every service tech that I've asked about this stammered around with a different answer, like they weren't sure ...?? does anyone here have advice for this ??
I am a diesel mechanic for a living and our shop swears by lucas dissel deep clean. it cleans the DPF. Every time the engine does a regen the DPF is not fully cleaned. Over time the regen cant clean the DPF enough and then the DPF will have to be replaced or cleaned. the lucas cleans that little amount of soot thats left behind. i use it in my ram 5500 every 3rd tank of fuel because my truck idles A LOT! 132K miles and not one DPF issue.
 

89Suburban

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I am a diesel mechanic for a living and our shop swears by lucas dissel deep clean. it cleans the DPF. Every time the engine does a regen the DPF is not fully cleaned. Over time the regen cant clean the DPF enough and then the DPF will have to be replaced or cleaned. the lucas cleans that little amount of soot thats left behind. i use it in my ram 5500 every 3rd tank of fuel because my truck idles A LOT! 132K miles and not one DPF issue.


Good advice there if it works, thanks for that. I assume this is good for heavy truck fleet diesels as well? DEF filters are kicking our ***** right now.
 

sqd pkl

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Good advice there if it works, thanks for that. I assume this is good for heavy truck fleet diesels as well? DEF filters are kicking our ***** right now.
We had a isuzu with a clogged DPF and it was so bad it wouldnt hardly run. After 2 tanks with lucas it was back to normal. Works very well.
 

Stbentoak

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I am a diesel mechanic for a living and our shop swears by lucas dissel deep clean. it cleans the DPF. Every time the engine does a regen the DPF is not fully cleaned. Over time the regen cant clean the DPF enough and then the DPF will have to be replaced or cleaned. the lucas cleans that little amount of soot thats left behind. i use it in my ram 5500 every 3rd tank of fuel because my truck idles A LOT! 132K miles and not one DPF issue.
Does this product contaminate the oil? or can it be used at any time when a problem may be growing? Might be something to have around in latter DPF life to extend its useability... Also does it clean while you are driving or only effective during a regen?
 

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