What questions do you have for GM about the LM2 Duramax? 

Ross, thanks for the information. I agree with you about not going back as long as we have a choice :). I am guessing you have had the software updates done to your truck? Please keep me posted on how things keep going. I am going to ask about the oil usage, seems to be kind of typical but I'm still hoping the motor seals up a little better when it gets broken in.

Yeap mine used oil to

GM already announced they're upping the payload and tow ratings. It won't get the same ratings as the 6.2L configurations, though. Nothing physically changed on the trucks to warrant the rating adjustment, though. See here: gmauthority.com/blog/2020/09/2021-chevrolet-silverado-gets-increased-towing-capacity-with-these-two-engines/ From what I've been reading, it has more to do with getting heat out from the engine bay rather than anything inherent in the power delivery. They were being conservative on the 2020 models and found there was enough heat-rejection to justify an increase in tow/payload ratings for 2021-up.

I looked underneath I def think you could.... Just it would probably have to be purpose built for the application. I going to upgrade mine for sure... I mileage is great but I would like a bigger tank then 90Liters

For those of us in the US, it's 24 gal. for most configurations. The only exception is for the standard cab, long bed which gets a 28 gal. (107L) tank. There is absolutely more room for a larger tank, even with the 5'8" bed. Titan or TransferFlow are (probably, hopefully) going to have something for this soon. They'd be fools NOT to. Part of the reason the manufacturers have been trending towards smaller fuel tanks is for CAFE (Corporate Average Fuel Economy) standards. The less fuel on board, the less weight there is to carry around, the less energy is required to haul that weight around. And, with vehicles getting better and better overall mileage, there's less reason to carry the excess fuel for range purposes. I don't know if it's an official metric or just happenstance but most vehicles will range out at about 400 miles on a tank for "average" drivers (not hyper-milers, not lead-footed racers). So the manufacturers ask themselves, why carry around weight for excess range when it's just going to kill your EPA numbers and drop payload and tow ratings? For the record, I'm with you on wanting a larger fuel tank for better range and extended run-time. My plan is to tow a light-duty camper (under 7k lbs GVWR) and having more range is always nice.

Great question, you would think that all of the customer uncertainty about the belt is clearly holding people back. Is certainly doing that for me.

There is so much trouble with today’s diesels plugging up the EGR with soot and oil they had to find a way to reduce the time it takes for the EGR to plug up. That’s why there is a before the DPF and after the DPF EGR intake on these trucks. It’s not the cure but will run longer before the EGR plugs up. No oil pump chains pls you want gear drive...

I saw another interview video where a GM engineer said they were considering increasing the suggested 150K changeout recommendation based on their engine tests.

I think they will come up with all kinds of answers on this because they are seeing so much flack on this idea. And really... not much wonder..

This would be something ripe for the aftermarket to solve. Replace the pullies with sprockets and a long-life chain. Or insert an electric pump somewhere external, like the feed to the cooler. Maybe both... I see GM having a change of heart on this at some point, as well. First, a revised design that does exactly what I suggested the aftermarket does for the original LM2 in subsequent builds (LM3?). Second, a retrofit kit for those of us with the original belt-drive-oil-pump LM2. By the time the belt is ready to be replaced, I have zero problems dropping the transmission to get access to it if there's a long-life alternative to go in its place.

I gave this a like but would also like to point out you can get a PDF version free from GM directly, as well.: my.chevrolet.com/content/dam/gmownercenter/gmna/dynamic/manuals/2020/chevrolet/multimodel/2020-3.0-duramax-diesel-supplement.pdf That link is to the Chevrolet size but the supplement covers both GMC and Chevrolet. Also keep in mind that's the 2020 model year and another one is probably available for the 2021 trucks by now. Download that, along with the PDF of the owners manual, and keep a copy on your phone. And probably a copy on your computer at home, too. While you're at it, something I do with all my vehicles (and mowers, and other equipment) is to create a hot-list of common info. Make/model/year, VIN, engine info (including RPO code), common parts cross-reference (wipers, bulbs, fluids, filters, etc.), tire size, drain plug size(s), common torque specs - anything useful. Then I print a few copies and put them in the glovebox or center console. That way, when I go to buy parts at the local store, I don't need to rely on the clerk or their computer/book. I can get the exact part I need without wasting any time.

They say it’s weight saving and quieter But really it’s a bad idea. I know I’m the negative guy but really it’s just a bad idea.

@@robm3357 that's not negative that's common sense.

I am using an Android phone with Torque Pro software from Ian Hawkins. I use a high quality OBD2 Bluetooth adapter like OBDLINK MX or MX+ and in some videos I have use the Track Recorder option that is also from Ian Hawkins. Some of my future videos will be using a screen recorder to record Torque Pro since the Track Recorder tended to only run for about 15 minutes before my Pixel 2 would overheat and shut down. Thanks for the question and for watching.

It’s a light duty diesel that doesn’t make enough power to warrant the Allison ....

The Allison in the Hd is not a Allison, it is Allison approved built by GM

Personal experience here - not sure about damage but there is an interesting side effect of plugging in above 0F. Cooling fans kick on to high and stay that way until the truck rests for 6 hours. More detail here: gm-techlink.com/?p=12389 I had this happen to me back in February (in MN). Overnight low was supposed to be below zero but warm back up by morning commute. I plugged in overnight and got the exact behavior described. Went out to lunch, fans still running on high. Commute home, still on high. Let it sit overnight, condition cleared.

I have already seen issues with this system on RU-vid. I think it’s just stupid...

I added this the first week I had the truck. Works flawlessly! www.autostopeliminator.com/products/2019-silverado-sierra-autostop-eliminator

Thanks Woody, I am considering adding one, but it seems like a stupid feature that shouldn’t be there on a diesel in the first place that shouldn’t require a $90 hack and 2 hours of dismantling the dash in a new truck to resolve. I know, preaching to the choir...lol!

This is my second diesel but the first one that's turbo. I suppose the only thing I'd recommend is sticking to fuel stations that go through high volumes of diesel fuel. Diesel has a higher tendency to be affected by certain aging factors than gasoline - water, a certain diesel-loving fungus, etc. I tend to avoid the small corner shops that happen to also sell diesel and stick to the larger places where I see box trucks and like regularly. Otherwise, there's nothing magical, here. Regular maintenance and quality fuel are really all you need. Doesn't matter if it's a little gas lawn mower or a heavy-haul rig that does millions of miles going cross-country.

I, too, would like to know this. They had a 4.5L in the pipeline before the bailout and would have been a stellar choice for a "heavy-half" pickup. It got mothballed and we got the LM2, instead. Not saying the LM2 is a bad engine (it's really not) but they made some questionable choice bringing it to market (oil pump belt on the back of the engine...) I think a more conventional design with more displacement and less turbo pressure would probably do wonders for durability as well as payload and tow ratings.

GMAuthority obtained an answer for this already with specifics, from here: gmauthority.com/blog/2020/05/2021-gmc-yukon-at4-wont-offer-diesel-powerplant/ "The reason comes down to the 2021 GMC Yukon AT4’s unique front fascia, which includes a revised lower section that’s higher cut than the standard 2021 Yukon fascia. While the new fascia looks great and comes with a higher approach angle, adding to the AT4’s off-road worthiness, it also obstructs the intercooler and intercooler piping needed for the new 3.0L I-6 LM2 Duramax turbodiesel engine. Thus, the engine will not be offered on the AT4 trim level." Personally, I find it rather odd that the pickups have no issue with this but the SUVs do. They're the same chassis forward of the driver's seat, after all... Maybe that's the better question?

My girlfriend bought a new 5.3 and a month later I bought the 3.0. We’ve taken turns using both trucks to pull our 32 TT. My 3.0 gets 11-15 mpg loaded while her 5.3 gets 15-19 mpg unloaded loaded its only 7-9mpg.

The more miles you run, the more the diesel makes sense. I'll do some back-of-the-envelope calculations here. I ran a '15 Sierra with the 6.2L, a '17 Sierra with the 6.2L, and now a '20 Silverado with the 3.0L, and I keep meticulous fuel logs for all of them. Keep in mind that, at the time I got my Silverado, the upgrade price for the 3.0L and the 6.2L engine choices were the same but GM reduced the upgrade price on the 3.0L since then. The 6.2L trucks *on fuel alone* cost me $0.165 per mile with an average of 13.4 mpg over nearly 60k miles combined between them covering both highway and city driving. For the 3.0L so far, I'm getting $0.1225 per mile with an average of 21.1 mpg over about 6500 miles with, again, both city and highway driving - not fully broken in, yet, so that will get a little better once I hit about 12k-15k miles. But the oil for the 3.0L is expensive stuff at nearly $9/qt vs. less than half that for the oil required by the 6.2L. A full tank of DEF - usually about every oil change - adds another $30 or so if buying in the 2.5 gal cartons ($15/ea x2). And a fuel filter about every year or so to the tune of $20-$30. All things the 6.2L doesn't need or has an advantage. Based on my own real-world calculations above (at current average prices for 93 octane and diesel), the difference *on fuel alone* is between $.05 and $.07 per mile. To factor in the additional maintenance costs the diesel runs me, I'll assume a 10k mile service interval on the fuel filter and a 3500 mile interval on the oil change with DEF fill-up. The additional routine maintenance costs add up to a difference of about $.02 per mile over what it costs on the 6.2L. So the actual benefit to the 3.0L over the 6.2L is between $.02 and $.05 per mile. With the upgrade price of the 3.0L engine being less than the upgrade price of the 6.2L, it makes a whole lot of sense to go with the diesel. However, based on the initial purchase price of the 5.3L engine choice being LOWER than the 3.0L, you'd need to rack up a lot of miles at $.02 to $.05 per mile to make that work. From what I've read, the 3.0L upgrade from the 5.3L equipped LTZ/SLT trim costs $1000 now (it used to be $2500). Depending on how well you're doing on mpg and, actually, cost per mile, it would take between 20k and 50k miles before the diesel paid for itself.

I'm getting about 1500 miles per gallon of DEF and I'm not towing (yet). The general expectation is that you'll need to (nearly) fill the entire DEF tank on every oil change with a little reserve left over. For the record, I'm about to do my second ever oil change on this truck at 6k miles and my oil life monitor and DEF meter are matching pretty close.

These trucks use a lot of DEF when towing. I'm still working on my long towing trip video, Flint, MI to Harrisburg, PA to Austin, TX and then back to Flint, MI. During this trip I was getting between 366 mpg on DEF all the way down to 239 mpg. I'm looking for a way to describe why this is the case, I believe it has to do with Light Duty Diesel Emission Requirements when compared to Heavy Duty Diesel Emissions. As a preview, LD is some many mg/mile where HD are rate at mg/Hp. With HD if you are towing and getting half the mileage you will burn double the DEF, LD they need to keep that DEF Flowing to stay below, I think, 195 mg. More to come. One other comment that will come out in a video, the DEF gauge in the truck in no more than a guess, in my opinion. While towing it would drop 1 bar and the go right to "empty".... I blame this all on the other cheaters out in the market. GM needs to make sure that you never drive this truck when it is not in compliance, good for the environment but.... Thank for the question and for watching.

Horsepower or Torque? I want torque for pulling up the hills.

I just worked through a cost comparison between the 6.2L and 3.0L engine choices in another comment and, even factoring in the additional maintenance costs on the diesel, it still comes out $.02 to $.05 per mile better (depending on the relative costs of diesel and 93 octane premium gas). However, the 3.0L isn't rated to tow as much as the 6.2L. And the 6.2L can be equipped with the Max Tow package to increase that rating even more. Thing is, it has almost zero to do with the power delivery and more to do with how well heat is evacuated from under the hood (from what I've read and watched). That said, if your choice is between the 6.2L and the 3.0L *and you don't need the extra towing capacity from the 6.2L*, go with the 3.0L - it'll be the more cost-effective choice in the long run. However, if you are going to tow or haul more than the rating on the 3.0L, stick with the 6.2L and, optionally, with the Max Tow package. Also, having driven both, there's nothing that'll put a grin on your face faster than dipping your foot into the throttle in a mostly un-laiden truck with the 6.2L. Freeway speeds are obtained VERY quickly. The torque of the 3.0L is there off the line - more so than the 6.2L - but it feels like it drops off after about 35mph where it just turns into a slow-but-steadily-faster freight train. In other words, it'll get from 30 to 70 easily enough, regardless of load, but it won't be as... dramatic... getting there as the 6.2L does it. The equation changes if you compare the 5.3L and the 3.0L, however. The up-front cost to upgrade the 5.3L to the 3.0L is about $1000 and would take between 20k and 50k miles to break even (depending on your own average cost-per-mile). And it's actually probably longer than that because I failed to account for the lesser cost of 87 octane needed by the 5.3L giving it a wider gap to the 3.0L (the 6.2L really ought to be running 93 octane). If the 5.3L will meet your towing and hauling needs, it will absolutely be the better choice both up-front and over the long term.

What is the life expectancy of the LM2?

The EPA ratings were released today

I'm not affiliated with GM but I can tell you how the cooling system works. There's a traditional water pump in the usual location on the front of the engine. But, instead of a thermostat, there's a valve body that directs coolant where it's needed - the radiator, the heater core, and back to the engine. There's also an electric auxiliary pump for getting warm coolant through the heater core when the Auto Stop function kicks in and heat is called from the HVAC system. Page 5 of the following document at NHSTA has a less buzzword-y description with a color-coded diagram of that valve body: static.nhtsa.gov/odi/tsbs/2019/MC-10165111-9999.pdf As for issues, not sure what you're talking about, specifically. Does it run a bit warmer than previous trucks? Yes, and that's apparently intentional. Whether or not that's "good" is another matter entirely. Long term, I expect someone in the aftermarket is going to have a way to break the programming lock and set the upper temperature threshold a bit lower. I've seen mine regularly bound into 215F territory for short periods before dropping just under 200F again. And it's not due to the loads I'm carrying as I'm usually mostly empty nor ambient temps as it's happened in the summer in 100F heat as well as Nov. temps as low as 15F. I get the feeling that it's programmed to keep the active shutters closed and not circulate to/from the radiator until there's enough heat load to justify opening those shutters for MPG purposes. I did have one instance late last winter where I plugged in my block heater when it wasn't below zero Fahrenheit but certainly close to it. The truck went into a mode where the cooling fans ran full-speed full-time until I let it sit for over 6 hours. It's apparently a known issue that, at the time, GM says a fix is coming. But I haven't looked back at whether or not that fix is ready, yet.