New to diesel - help needed

[sskyway2]

I'm considering getting a 2025 Tahoe Duramax (when they come out) primarily because of their perceived reliability. I've never owned a diesel car before and there's a lot of terminology I don't know about (ie regens, DEF). Can anyone help explain these terms and what difference in routine unkeep / maintenance I would expect versus the 5.3/6.2? Thanks.

 

[89Suburban]

@Stbentoak @StephenPT

 

[JayceeP]

Just make sure the DEF tank is full when you drive it off the lot and all will be good lol.

I’m new to diesel this year with a ‘24 Yukon XL SLT…. Over 6,000 miles now since May. Runs great, fuel economy is stellar, and regen has never been an issue.

I did have a DEF range issue when towing a jet ski this summer on a 500 mile trip but I realized my DEF tank was probably not filled when I bought it and drove it off the lot end of April. There was a software update pushed through eventually as well because I couldn’t get the message to go away. This was in August.

Since then my DEF gauge has dropped only 1 bar and no issues since.

Most annoying thing about my ‘24 Yukon XL SLT is no permanent fog light setting, the steering wheel and driver seat positioning, and the temperature gauage doesn’t do 0.5 degree increments. Not an issue in F but in C going from 22 to 23 or 21 degrees is a noticeable difference so I always seem to have to adjust the temp setting super annoying but all of this is unrelated to Diesel.

Zero regrets as far as the diesel goes. 2025 will get the LZ0 engine which means a bump in horsepower and, presumably, a little bit more highway pull when passing.

Enjoy!

 

[PPV_2018]

Def = horse piss you pour into a separate tank to keep the epa overlords happy.

How many miles you get out of a tank fill varies, but you’d probably not be refilling DEF often unless on heavy towing duty frequently.

 

[Z15]

Fwiw, the DEF tank is suppose to be filled to capacity during dealer prep. DEF use is related to how hard the engine is working and towing is working the engine and more DEF use is NORMAL.

 

[Stbentoak]

Well, there's lots of things to "know", but most of them are simple and inconsequential... you may want your DEF full when you leave the dealer, But I never run mine completely full. There's nothing wrong to keep it full, but I prefer to keep it in the middle range and refill it when it indicates its first warning.. I can dump 2.5 gallons in and I'm good for at least 5000 to 7500 miles. And oil changes are no different than any other vehicle other than that you need to use Dexos D oil.. It's readily available even at Walmart and I use an AC Delco gold filter. I push it at least 6000 miles, except for the initial change at about 3000. Blackstone tests have proven this oil can go way beyond 7500 miles, really. But I'm trying to comply with warranty. Buy DEF at Walmart. They turn it over weekly. It's always fresh and the container makes a great oil change container to take to dump the waste oil. Fuel filter change takes 15 minutes. It's right underneath the driver's door And only really needs to be done about every 25,000 miles. I've changed mine twice and it looks pretty much like new each time I've changed it. It runs fantastically, My worst mileage is 20 miles per gal. That's usually in tough city driving in cold weather. I average 27 on any given moment and have pushed 32 on the highway.

I'm very satisfied with this vehicle. It's had a few problems. They've always been fixed reasonably quickly by the dealer and none of them had to do with the engine. Mostly electrical airbag issues. I like it so well I ordered a 25 Denali ultimate LZ0. I can only hope it will be as good as the one I have now.

This engine was designed to be about the most consumer-friendly diesel out there.... it warms up very quickly and doesn't exhibit really, any quirks of a diesel as you may think of in the past. None of my friends even suspect is one till I tell them and then tell them what kind of mileage I get. They are shocked, frankly, as most cars they are driving don't even get as good of mileage as this vehicle.

 

[Z15]

I don't need any DEF but I been to WM several times since I got this truck and they are always out of DEF. The space on the shelf shows they don't stock much, about 3 ft of shelf space. My SM gave me a gallon of AC Delco DEF with my truck and I have yet to use it 6 months later. 4,000 miles, gauge is only down 2 bars which is about 1 gallon per owner manual. DEF per SDS is 67.5% water, 32.5% urea.

 

[martinajm]

I am 3 years into my 1st diesel - 2022 Yukon XL. There isn't anything that should intimidate you.

DEF - Diesel Exhaust Fluid - a fluid stored in a separate tank that is injected into your exhaust to reduce emissions. Pretty typical to get 1000 miles per gallon unless you are towing. You can buy 2.5 gallon jugs just about everywhere you can buy fuel plus many other places, i.e. Walmart. I choose to use the DEF pumps found at most "truck stop" type gas stations. Generally if it is a new station and it has diesel only pumps they should have DEF pumps as well. When I am towing heavy on a long trip I usually throw a 2.5 gallon jug in the back "just in case." If you do spill any on the truck, be sure to wash it off.

Regen - Every so often, the vehicle will burn off the particulate that is captured by the exhaust filter. This is simply an automated process that increases exhaust temperature to burn it off. The only way that I have ever been able to tell that it is happening is that the idle will increase a couple hundred RPM when you are at a stop light. Some people have reported that he4y can smell a regen if it happens in a garage, but I have never experienced this.

Oil changes are usually a bit ($10) more expensive because they generally hold more oil. Pretty much the same process and I image the same recommended interval. I choose to get my oil changed at the dealer, as I can buy 6 at a time and they do a good job checking everything over - just beware of the upsell on "Dealer Recommended Maintenance" which I have found toe be well in excess of the GM recommended maintained.

Fuel Filter does need to be changed more often than a gasser. I change mine when the computer says about 50% life left. Costs about $0 for the OEM filter or about $10 for aftermarket on Amazon. Only "special" tool that you might need is a 36 MM socket (I think that is the correct size). Changing it your self takes about 10 minutes and I do mine with the vehicle on the ground. Dealer charges a couple hundred buck for this!

It amazes me how many people trash the diesel, but I think they are looking for excuses not to like it.

The best part of the "routine" is only filling up every 700 miles!

 

[Z15]

The same company that makes AC Delco DEF makes

https://www.owi.com/retail/brands/bluedef/diesel-exhaust-fluid

 

[Fless]

Fuel Filter does need to be changed more often than a gasser. I change mine when the computer says about 50% life left. Costs about $0 for the OEM filter or about $10 for aftermarket on Amazon.

Link to the inexpensive OEM filter?

 

[martinajm]

Link to the inexpensive OEM filter?

TYPO! $40 for the OEM

 

[Jay P Wy]

Cheapest place to get OE TP1015 is Rock Auto at about $28 plus shipping. Be careful on Amazon, most of the filters are not genuine GM/AC Delco filters. FYI the filter is the same as the 6.6l Duramax (L5P) uses so they are easy to find.

 

[sskyway2]

Thanks, all for the great responses

 

[Z15]

Seen a video of the AC Delco GM 3.0L/6.6L fuel filter. The Mann+Hummel, WIX and AC Delco were identical down to every detail including stenciling on the filters. Can't find the link right now. Mann+Hummel owns WIX.

GM does not make filters anymore, they bid it out.

 

[Stbentoak]

The same company that makes AC Delco DEF makes

https://www.owi.com/retail/brands/bluedef/diesel-exhaust-fluid

And very well could be the same place that makes Peak "Blue DEF" and or Wal Mart DEF. It is all the same stuff, so no reason to overpay for it. IE; WM DEF 9.00.... Peak DEF 16.00.
Idential product in container.

 

[Barnum]

I have 3 years with my Denali Duramax. I love the fuel mileage but have had an issue losing a cylinder, the DEF system injector failing and a crank case leak. These have all been fixed under warranty. It is a 2021 model and I consider it a COVID build. The Engine is fine I am just concerned with longevity of the DEF system and the expense that may have long term. Most importantly after having the 5.3 and the 6.2 I absolutely miss the top end power. I have a new 2025 Ultimate on order and I chose to go back to gas. If I towed more or put on more long distance interstate driving I may have chosen differently.

 

[CTown Duramax]

Get one. 2021 Duramax Tahoe, no problems at 35k miles and 40 months. The engine is a joy to drive. The 460lbft of torque available from 1500 rpm lets the Tahoe move effortlessly. 0 - 60 is always under 8 sec. Keeps accelerating beyond 80+. I would always get a diesel.

All this turbo diesel tech has been worked out for every day use like a gasoline engine. The Euros use these engines everywhere all the time for all purposes. The diesel is considered the better, more expensive engine. I use ours in an urban setting all the time, school, groceries, cross commute, trips, just like a gasser.

Tahoe's overall build quality is like German cars but the ergonomics are way way better.

 

[ducfan]

Just make sure the DEF tank is full when you drive it off the lot and all will be good lol.

I’m new to diesel this year with a ‘24 Yukon XL SLT…. Over 6,000 miles now since May. Runs great, fuel economy is stellar, and regen has never been an issue.

I did have a DEF range issue when towing a jet ski this summer on a 500 mile trip but I realized my DEF tank was probably not filled when I bought it and drove it off the lot end of April. There was a software update pushed through eventually as well because I couldn’t get the message to go away. This was in August.

Since then my DEF gauge has dropped only 1 bar and no issues since.

Most annoying thing about my ‘24 Yukon XL SLT is no permanent fog light setting, the steering wheel and driver seat positioning, and the temperature gauage doesn’t do 0.5 degree increments. Not an issue in F but in C going from 22 to 23 or 21 degrees is a noticeable difference so I always seem to have to adjust the temp setting super annoying but all of this is unrelated to Diesel.

Zero regrets as far as the diesel goes. 2025 will get the LZ0 engine which means a bump in horsepower and, presumably, a little bit more highway pull when passing.

Enjoy!

Thanks for this post. Wondering how DEF has been going when towing now that you have the software update?

 

[petethepug]

GM’s baby Duramax is the industry’s best kept secret.

 

[LEsoftballdad]

I have the LM2 engine in my 24 GMC Yukon SLT. While it is a good performer, I do not get anywhere near the mileage others claim to get, and I have taken several long road trips. The best I have ever done was 31.1 over a 50-mile stretch, but I was stuck in traffic, moving 45 MPH. When I am on the highway at 75 MPH, I get about 25-26 MPG.

I get my DEF at Home Depot. They have the least expensive stuff available, and I only fill it every 5K.

I recommend not getting a diesel if it's for driving around town on short trips. You want to use it on the road. Also, be prepared to see wild swings in fuel prices. Right now, diesel is about $1 more per gallon than regular unleaded.