mark1968

I really appreciate the comments! I was also thinking that the ZR2 Bison is heavier than the Denali and less aerodynamic so that could be part the difference.. On our normal round trip run of about 2k miles, on the old Denali we would get about 24 mpg.. On this trip we just finished we got about 21 mpg.. I expected lower mpg due to the lift but had not considered a big DEF difference.. I guess ill keep monitoring and see if it is around the 2% of fuel usage. As a side note, we do love the truck.. it is a beast and more suited to the remote area we live in now.. What’s interesting is our son also just bought a Trail Boss with the new 3.0 and I drove it back to East Coast for him. Even with the lift i didnt see the level of DEF usage we saw on this trip with the ZR2. So there must be a factor of weight and we did have some headwinds coming West yesterday.. Anyway, thanks again for everyone’s thoughts!

So we were fortunate to buy one of the new 3.0 diesels in early 2020. We enjoyed that GMC denali for the last few years but with all our long distance driving between our kids/home, it was reaching 100k miles and I read great things about the updated 3.0 (LZ0) and decided to trade in our 2020 and get a 2024 ZR2 Bison with the 3.0. For the last week we have been breaking the new truck in and driving across country. We were very used to the DEF usage on our 2020 and with a 1000mile trip we’d normally (not towing) see about 2 blips down on the DEF guage. However with the new truck, we are seeing significantly more DEF usage on basically the same trip (more than half way down) so we are kind of surprised. I know Ive read of other owners who had the original 3.0 diesels engine and traded up to the new LZ0 one, so what has been your experience? Love to hear feedback?? Thanks!

Hi KinkyDuramax- only issue we had was the early on recall to address an oil issue, then at about 60k miles, one windshield wiper motor went bad and finally at about 87k, we had a coolant hose crack which did leave us stranded in ND, but it turned out to be an easy fix. With all our back/forth across country driving, I do keep eye on oil and have to add some from time to time between oil changes, but thats about it.. We love this truck but i do have an itch to move up to the new LZO engine.. But we’ll see…

Thanks. I appreciate the responses.. Our 3.0 engine was part of a limited recall early on for burning oil but since that time, we’ve only had a windshield wiper motor and coolant line failure (this did leave us stranded tho). We love this truck and alternate it with our 2022 Silverado 6.2l to drive back/forth from our homes. My wife really wants something more lifted and beefier so we’ve been looking at ZR2’s with Bison package.. But I think you’re right- we dont owe anything on it and its been a great truck even with the issues.. Ill have my local dealer do the 100k maintenance and see how it goes.. If we get another “stranded” issue before the 150k oil pump belt change, then ill trade it in..

I currently have a 2020 GMC Sierra Denali with the 3.0 and im getting very close to 100k miles when my extended warranty will run out. We love the truck and the mileage we get but Im a tad bit worried about going over 100k miles and am thinking i should be looking at trading it in on a newer one with lower miles. Id love to hear folks input who have over 100k miles on their 3.0 diesels and if they’ve seen any problem areas pop up.. Thanks!

So i just got my 2020 back with the new/updated camshaft and glow plug replaced and tomorrow we take off for another 2k mile trip to see how it does. Ill be frequently checking the oil level on the entire trip and crossing my fingers.

We have a 2020 GMC Sierra 1500 with a 3.0 and at 28k miles I noticed the oil dropping quickly after oil changes (note i only noticed this as i checked my oil before/after a long trip- no warnings or codes thrown). I took it to our dealer and they found a TSB on certain serial numbers that were produced where they said this could be an issue with the camshaft housing and mine was in the range, so we did an oil test. Same result - oil dropped quickly so the truck has been in since last week getting the same fix that is mentioned above. I am hopeful this will fix the issue however based on the fact that now im hearing/seeing 2022’s with the same issue, that is concerning as the dealer mentioned that this issue was limited to a group of engines that were produced. Oh well, if it keeps being an issue after fixed, ill just trade it in on a new one as we love this truck and this engine despite this issue. (And to answer the question in the first post, yes we have the same amount of oil disappearing and i don’t believe our dealer either has done one of these fixes. I was lucky as initially the dealer was mystified by this but apparently a GM tech was in the shop the day i brought the truck in not showing any oil on stick after the dealer had just changed the oil 2k miles before and he knew about the TSB on this.)

Huh well go figure… I did call the executive line and they said that I DO have to pay a diagnostic fee if they couldnt replicate the issue. Seems really awful especially since we’ve all seen the “ghosts in the machine” software issues pop up in these trucks that the dealer couldnt find nor replicate and yet eventually becomes a big enough issue where GM has to issue a bulletin for a fix months later. Ive never had this come up with any of my cars before no matter the brand unless i was out of warranty. Maybe this dealer is just a bad, greedy dealer (note- they were the same ones on my first oil change put the wrong oil -Dexos instead of DexosD- in the engine and i had to call them out and they grudgingly admitted mistake and fixed it). I guess i should have learned my lesson then. Ill be going to another dealer (further away) from now on and certainly never buy another car/truck from them and tell everyone i know about their poor service. I hate doing that but the whole thing is disappointing.

Thank you for the input/advice and what path to go down.

So we just got back from a long road trip with our 2020 Sierra 1500 3.0 diesel. The truck did great and we got terrific mileage. However on the trip, we noticed several things- high usage of DEF compared to previous road trips (no towing); back up camera had a black screen a couple times; and carplay would intermittently not connect to my plugged-in phone. We took it to the dealer today to change the oil and rotate tires and check out these things 3 things. They discovered there was an update that needed to be done to address DEF issue; back up camera requires a new module which is back-ordered and they could not replicate the carplay issue. Ok im fine with all that however what puzzled me is that they charged me a “diagnosis fee” for them not finding any issue with carplay?????? Im still under my 3 year/36k warranty and them charging me a fee to tell me what i hear many of you say on this board “cannot replicate issue” seems way out of line to me.. Am i missing something or out of line questioning this charge? Advice?

Agree with Grover. When we’ve traveled both to East Coast and West, we never had a problem finding fuel as trucking is critical to movement of goods. And you are spot on about DEF- if we dont tow, it barely uses any even over a 1k miles.

We just got back from a round trip from MN to VA to IL to MN over the last few day to drop kids off at 2 different colleges. Our truck (2020 gmc 1500 denali 3.0) did amazing the entire trip. Recap: 2550 miles with avg of 28.4 over entire trip and only 2 blips down on full def tank- we didnt tow anything. In fact a full tank looks like it could almost do 800 miles total on the open road. Truck now has 18k basically trouble free miles on it now. We are thrilled- very comfy and cruises the open road perfectly.

So i wrote about my experience earlier when i took my new 3.0 in for first oil change. I did email and call before setting appointment and verified they had correct oil. I dropped it off at the dealer and reminded the service advisor about the special oil. Once again no problem. Picked truck up and took it home and looked at the receipt— WRONG OIL. I took it back and made them change it again with the correct oil. I called the dealer manager and let him know. Really pathetic...So you can call and check, but verify when picking up.

So I actually have a follow up on my original post and the wrong oil and it just keeps getting better- Frankly despite giving dealers an opportunity/second chance to show they are competent, they fail over and over. So its been 2 months and we’ve put 2k miles more on the truck since the 1st oil change. Yesterday i decided to do a thorough check on everything and I checked the oil level. Well wouldnt you know it, no oil on dipstick. I looked at the pan, no drips, leaks- all clean. Huh.. Well i rechecked the invoice from the final “corrrect oil change” and it stated 7qts dexos d 0W20. Well thats correct- so where is the oil going. I dropped off the truck Saturday at the same dealer to figure this out(i wanted it all documented in the system)- and they confirmed- no leaks, no nothing.. So they said, it must have been incorrectly filled originally. Frankly I have no idea if its 1 qt down or more and they couldn’t tell me as they have no dexos d in stock to fill it. So they are keeping the truck till monday. Seriously-how dumb do you have to be to correctly refill the oil after change. Now my BIG MISTAKE was NOT checking their work when i originally got the truck home. I had assumed since I had talked to the general mgr of the dealership about the original wrong oil mistake, they would do it right on the second try— NOPE. So lesson for me- after you overpay for any work at a dealership, you have to double check their work. That is so pathetic- If i ran my biz that way, I’d be out of business. I live in Minneapolis and if anyone wants to know who this incompetent dealership is and the one to avoid, you can PM me. Thank for letting me rant...

Yes this pretty much fits my experience so far around town and a bit of highway. We have 9k miles on our truck. And i do agree, hand calculated seems to be higher than the truck computer. We love our truck.

Purchased early January- 9200 miles now. Several trips back/forth from MN to WY. Just got home from one of these round trips- averaged 26mpg at 80 mph. When the interstate went down to 1 lane and 65 mph, we were getting over 31 mpg. Overall the truck did great again. For the 1000 miles, the DEF dropped 2 bars but we weren’t towing anything. What was most impressive was when we went offroad looking at some land. Despite some gullies and hills, the truck did great handling it all and the ride stayed surprisingly smooth despite the rough lay of the land. We have a crew cab with the denali trim. Still very happy overall.

After reading this board and others so i was fully I informed, I dropped my 2020 GMC 3.0 at the dealer for its first service/oil change. I made sure to point out to the service writer several times that i wanted the correct oil as this truck had specific requirements. I even gave him the specific type so they would screw it up - Dexos D 0-20W. He said no problem, they do lots of gmc diesel truck oil changes. I even called him back later that day to double check they were putting the right oil in. Once again- no problem, we’ve got this,etc. Ok get notice truck is done and my wife goes to pick it up. Last night when i got home she gave me the paperwork they gave her and guess what—— WRONG OIL.... they put in 6 quarts Delvac 15-40W. Sigh.... This morning i emailed the general manager very nicely about this and he called me back. He checked and they have the Dexos D 0-20W there and now I’m dropping it off again. So lesson for everyone if that hasn’t been repeated enough in this thread and others, check, check and recheck what they are putting in your truck or do it yourself to be sure!!! PS- thanks for all the knowledge I’m gleaning from all of you...Otherwise I’d be a dumb consumer!

So we got our 2020 3.0 Crew cab/short box denali in December and only had the chance to put a couple thousand miles on it. ‘This week we finally got to take it on our first big trip out west. We are half way through the trip and going through SD and WY we avg’d about 75-80 mph. We have 4 people in the truck and bed has luggage and supplies and we are getting about 25mpg. I realize if we went 55mph that we’d probably get closer to epa numbers but I’m pretty happy with this result. Additionally before this trip, with around town driving, we were getting consistently getting 24-25. We took this same trip a few years back with our suburban and averaged about 18-19 mpg. Overall truck is doing very well and no issues- Its a pleasure to drive and comfortable for all.

I agree. We’ve had our truck now for 3 months and most trips are short. Haven’t had any issues with regen and mileage has been averaging 24-25 around town.

We’ve had ours for a bit over a month now and 1200 miles. Only one issue with black screen which was fixed by dealer with update. No other issues but have noticed the coolant temp running up and down too. Our “around the town” mileage is about 24mpg so far and it drives so well with the suspension that makes it feel more like a car than a truck. We still have not tried remote start on it yet even with the temp getting down to -10, however when we crank it during the coldest temps, it starts up fast.

Couldnt agree more. We never had any issues with our TDI's and even after the "fixes" they are pretty much as they were before. So all good. .

We just picked up our 2020 Sierra 1500 Denali diesel today. For the 70 miles we've driven it, we are happy with the purchase. I really wanted the SLT with X31, but when we drove it and then the Denali with Ultimate (both diesels) my wife really liked the ride on the Denali better. Since she will drive it more than myself, I felt that was the way to go. This will be our 3 diesel in the family with the other 2 being Audi's. For some reason, I really like them (along with the vastly superior fuel economy).