Help Educate Me On Owning a HD Diesel Truck

[DAI]

Since the order is in and now waiting for it to be built (2024 GMC AT4x HD Duramax), I figured I start educating myself on everything I should be doing with owning a diesel.  I’m already mentally prepared for higher maintenance costs, but have some other questions:

• Should I run fuel additives, and if so how often and any recommended ones?
• At what overnight temps should I consider plugging in the block heater?
• This will be a winter/poor weather daily driver, and my commute is ~25 miles mostly at 45-60 mph on the way in and ~75 mph on the way home.  Is that enough to warm up the engine to prevent soot build up?
• Since the engines typically don’t run hot, should I still continue to use full synthetic oil?
• Other things I should know or do?

[Nick55]

Here, the manual for the 2024 Duramax engine.  Get your info right from the source.  

https://www.gmc.com/bypass/pcf/gma-content-api/resources/sites/GMA/content/staging/MANUALS/8000/MA8666/en_US/2.0/24_MUL_Duramax_Diesel_6.6L_SUP_en_US_U_84989064B_2023JUN02_2P.pdf

My $.02 as someone who has had Duramax trucks before AND is in the industry and deals directly with these engines and powertrains:

•don’t run any additives that the manual doesn’t call for.   Fuel may need an anti-gel in cold weather if you have warm season fuel and it gets cold.  It may also be needed if temps drop significantly.  
•see the manual regarding plugging in and use of winter fronts to block radiators - do either wrong and you will get check engine lights, possibly derates as well. 
•repeated 25 mile trips will not likely be enough and you may have problems with having to stop for a regen occasionally.  Again, read this manual and understand what is needed

•the manual will specify the oil grade you need to use, most likely it will be a synthetic 

•if you can’t use this truck like a truck and tow with it or get it out on the highway, it’s likely the wrong application for you and you may have excess soot and emissions systems issues.  
These are complex engines and exhaust systems, the more you understand about it, the better your experience you will have with it.  
DEF does have a shelf life, so if the truck sits months on end, or isn’t used enough, you will have issues with the DEF system too. 

If all of this is fine with you, now you have time to shop for the light bars and big chrome wheels, steps, hitch receivers, and bed covers (that’s a whole ‘nother forum worth of topics to cover).  I kid about most of that, but I do recommend a bed cover of some sort unless you have a fifth wheel too.  Plan well and you can build/buy racks for surf boards and other toys for the bed that could be locked under a cover if you don’t want to keep them in the boat as you tow. 

[BlindSquirrel]

@DAICongrats on the new ride. I've had a Cummins since 2018 and experience with my brother's 2020 Duramax. Here are my opinions on your questions.

Fuel additives: Yes, for sure in the winter. I use hotshot brand additives, seem to work well. The fuel stations do switch to a winter blend to help with no gelling in cold temps, however it's hard to tell which ones really do.... my brother's truck gelled at 10 degrees last year. Diesel 911 additive worked to un-gel the fuel in like 15 minutes. Now he uses Hotshot winter and has not gel issues. I have used hotshot brand EDT (every day treatment) for summer driving, it came free with my winter order, and got a 1.5 MPG better. Not sure if I'll buy more when I run out, but it does seem to make an impact.

Plugging in: Plugging in does benefit the motor by helping it start in the cold, but the biggest beneficiary is you. Warm air out of the vents at start up. These trucks have good glow plugs and even heating elements that heat the intake air, so they do pretty well on cold starts on their own. That said, I plug mine in on a wall timer to turn on an hour and a half ahead of when I'll be needing it. My brother has never plugged his truck in and says it starts just fine. Historically I treat my toys much better than he does. I assume you get better mileage and it's easier on the motor... so around 35 degrees or so I start plugging mine in.

Soot? In the winter, maybe 25 miles will be enough to get to temp but probably not. It depends on how cold it is and if you use the bra. I highly recommend using the bra to help it to get to temp and stay there. I put it on my truck when it's around 25-30 degrees. The soot cycle should heat itself up, at least my truck would. It didn't seem dependent on the engine temp. You'll know it's doing it as it smells different, and maybe you get a notification on the dash. Def does freeze too, it has a heater in the tank, but I've read in the winter to keep the level above 1/2 if possible. 

I use the same oil I use in my bu, regular ole Mobil Delvac 15 w 40. I do use the OEM filters...oil, fuel, and air.

People talk about the high cost to maintain these machines, but if you take the time to do it yourself... it's really not that much more. It's all easy to do.. The feeling I get while towing is well worth the extra for fuel and whatever else.

 

[pauley71]

Find a good diesel provider.  We have Southern States which has SuperGold 50 centane diesel and its actually cheaper than my local Exxon.  They include additives and my Super Duty runs like a different vehicle when using it.  Most 'gas stations' provide 40 cetane (at least around here).

[jjackkrash]

I put diesel and DEF in diesel vehicles as required and take them in for service when the computer tells me.   That's it.  It's not that cold here though.  I get free oil service for life from my dealer and haven't paid for an oil service since 2010 ish.  The trucks get fuel filters around 20-25k and things like that.   I have never had any real issues with any diesel truck I've owned--and never any emissions problem--but I also flip them more regularly than some.  I like driving newish trucks so I might not be the best sample.  

 

Edit:  Now that I think about it I guess I do toss SeaFoam in once in a while when I get it for the boat and such.  

Edited December 1, 2023 by jjackkrash

[Cole2001]

I have never ran fuel additives but I am in Canada and am 100% sure that we switch over to winter diesel well before it's needed. My suggestion would be to get diesel from truck stops or larger gas stations, that way you're getting fresh diesel that is less likely to cause issues. 

Also never used my block heater but I do park partially inside for the most part but still gets below freezing and has been fine. As long as your batteries are good a new diesel will start just fine at -30 but if you have power I would plug it in if significantly under freezing. If it is cold it should automatically go into a high idle to warm up but if it doesn't you manually do it. Or just little things if i stop at the gas station or get a coffee shortly into my drive I will just leave it running when cold. 

Don't be afraid to open up the throttle and use the turbo and exhaust brake. 

[RyanB]

I’ve owned diesels since 1998. Never have used fuel additives. Read your owners manual before you do. 
 

Cummins only recommends Power Service Diesel Clean additive.  Nothing else. 
 

DEF does have a shelf life, but from what I’ve seen it only increases usage if its past its expiration date, it won’t harm the system. 
 

I buy DEF either at the pump (new Maverick stations have it) or at Walmart in their blue jugs. 
 

My truck lives in a heated garage, but it starts fine elk hunting in below 0 weather. It does need a few minutes in those temps before it has any power. 
 

New trucks will tell you when you need a fuel filter. Pay attention to that message. 

[Bluefishcay]

Having put a lot of miles on diesels, much depends on each vehicle.  My e350 needed to be plugged in to start below 32 reliably.   My TDI’s would start down to -12f without being plugged in.  Below that I had to plug in and remove the batteries to warm them enough to fire.  But I would plug it in below freezing as it warmed up faster and started better.  
 

additives are not necessary unless you are going from say Florida where it’s 70 to the Midwest where it’s 0.  Then it can be the difference between being gelled up or driving.  Just don’t wait until it snaps cold to try and find antigell. It will be sold out.  I also kept a box of disposable gloves in my car to keep my hands from smelling like diesel.  It doesn’t evaporate like gas so any spilled on the handle stays there and the smell doesn’t go away quickly.  

[oldjeep]

Have you got a lift, super wide tires and a flat bill hat on order?  The come in a kit, if you get one you need all 3.  

[DAI]

16 minutes ago, oldjeep said:

Have you got a lift, super wide tires and a flat bill hat on order?  The come in a kit, if you get one you need all 3.  

First 2 are stock from the factory 

[oldjeep]

11 minutes ago, DAI said:

First 2 are stock from the factory 

Not the kind of lift and wide tires I am talking about.

Edited December 1, 2023 by oldjeep

[carguy79ta]

2 hours ago, oldjeep said:

Not the kind of lift and wide tires I am talking about.

Have to say I like that truck...I prefer the tires more flush with the side of the truck. Good looking truck tho. But too much lift and tire for me to spend my money on.

My truck..

[Stevo]

5.5 lift on 38’s- and I got your flat bill right here 🤌 

 

Edited December 2, 2023 by Stevo

[Stevo]

30 minutes ago, carguy79ta said:

Have to say I like that truck...I prefer the tires more flush with the side of the truck. Good looking truck tho. But too much lift and tire for me to spend my money on.

My truck..

https://www.instagram.com/p/CzfL15UJ4_m/?igshid=MzRlODBiNWFlZA==
 

go with a level kit on 37’s or step up to the plate with the Carli 3.5 dominator

[hethj7]

Just like the enthusiasts on this site where we nitpick all details and mods for our boats, I found in my research the diesel community does the same.   I was worried about cetane, water in fuel, etc. right up until I took delivery of my truck.   55,000 absolutely trouble free miles later and all I do is fill up at high volume stations, get my oil changed regularly at the dealer, and top off the DEF (which is very rarely unless towing a lot).   My normal commute is just a few miles to my office, so barely enough time to warm up often.  The Ford supplemental cab heater provides decent heat very quickly.    

In Kansas City, I certainly have days driving in below freezing conditions, etc.  I never plug in and although I'm typically parked in my garage, I've had plenty of cold starts when left at he airport or office with no issues.  I can't speak for results if I lived in a colder place like Minnesota, but in KC, zero issues so far.   

 

[DAI]

22 hours ago, Nick55 said:

Here, the manual for the 2024 Duramax engine.  Get your info right from the source.  

https://www.gmc.com/bypass/pcf/gma-content-api/resources/sites/GMA/content/staging/MANUALS/8000/MA8666/en_US/2.0/24_MUL_Duramax_Diesel_6.6L_SUP_en_US_U_84989064B_2023JUN02_2P.pdf

My $.02 as someone who has had Duramax trucks before AND is in the industry and deals directly with these engines and powertrains:

•don’t run any additives that the manual doesn’t call for.   Fuel may need an anti-gel in cold weather if you have warm season fuel and it gets cold.  It may also be needed if temps drop significantly.  
•see the manual regarding plugging in and use of winter fronts to block radiators - do either wrong and you will get check engine lights, possibly derates as well. 
•repeated 25 mile trips will not likely be enough and you may have problems with having to stop for a regen occasionally.  Again, read this manual and understand what is needed

•the manual will specify the oil grade you need to use, most likely it will be a synthetic 

•if you can’t use this truck like a truck and tow with it or get it out on the highway, it’s likely the wrong application for you and you may have excess soot and emissions systems issues.  
These are complex engines and exhaust systems, the more you understand about it, the better your experience you will have with it.  
DEF does have a shelf life, so if the truck sits months on end, or isn’t used enough, you will have issues with the DEF system too. 

If all of this is fine with you, now you have time to shop for the light bars and big chrome wheels, steps, hitch receivers, and bed covers (that’s a whole ‘nother forum worth of topics to cover).  I kid about most of that, but I do recommend a bed cover of some sort unless you have a fifth wheel too.  Plan well and you can build/buy racks for surf boards and other toys for the bed that could be locked under a cover if you don’t want to keep them in the boat as you tow. 

Thank you for sharing the manual; good pre-read in advance of delivery.  

First on the list to get is a Ride88 in bed bike rack and a tonneau cover that works with the rack.

[DAI]

19 hours ago, pauley71 said:

Find a good diesel provider.  We have Southern States which has SuperGold 50 centane diesel and its actually cheaper than my local Exxon.  They include additives and my Super Duty runs like a different vehicle when using it.  Most 'gas stations' provide 40 cetane (at least around here).

I’m typically pretty loyal to Shell (2nd is Exxon/Mobil).  I’ll have to check the pumps at the couple stations I stop at most frequently.  They are not truck stop volume, but do see a lot of diesel truck traffic.

[DAI]

8 hours ago, hethj7 said:

Just like the enthusiasts on this site where we nitpick all details and mods for our boats, I found in my research the diesel community does the same.   I was worried about cetane, water in fuel, etc. right up until I took delivery of my truck.   55,000 absolutely trouble free miles later and all I do is fill up at high volume stations, get my oil changed regularly at the dealer, and top off the DEF (which is very rarely unless towing a lot).   My normal commute is just a few miles to my office, so barely enough time to warm up often.  The Ford supplemental cab heater provides decent heat very quickly.    

In Kansas City, I certainly have days driving in below freezing conditions, etc.  I never plug in and although I'm typically parked in my garage, I've had plenty of cold starts when left at he airport or office with no issues.  I can't speak for results if I lived in a colder place like Minnesota, but in KC, zero issues so far.   

 

This sounds very similar to what I noticing/going through yesterday.  

[hethj7]

2 hours ago, DAI said:

This sounds very similar to what I noticing/going through yesterday.  

Yea, I think sometimes we all forget that Ford, GM, Malibu, whomever designs these things for the masses and to be reliable.  They spend millions in R&D and know the general consumer just wants to push a button and go, tap a screen and surf, etc.    

Us 1%ers are the outliers in use cases.   Ford/GM knows plenty of their trucks are headed to cold climates and their manuals should address at what point you need to do something different for those use cases.   

[UWSkier]

FYI, GM doesn't include 12v cigarette lighter sockets on the 2024 trucks.  If you have 12v accessories, you need to find a workaround or install one aftermarket.  That was an unpleasant discovery on my new truck.

[MLBurns]

Best advice I can give to a diesel owner is don't leave DEF tank low on fluid very long. The fluid will crystallize when it dries out and the fluid level gauge can stick causing false readings. I've experienced this on several trucks (Ram and GM). All I have ever run on Duramax's is Rotella 15W-40. I run all my trucks over 200k before selling them with no issues. My 15 Duramax was sold with 250k on it, current owner is at 450k now with it. I work in oil field out of my trucks so they run for 12+ hrs per day so 200k miles is a TON of run hrs. Nothing fancy as far as oils, just change every 5-6k miles. I have tried to do this with gas trucks, they will not make it 1/2 mileage as diesels. We have all makes and models out here in the field, all have pros and cons. Buy the truck you like, not what others want you to get.

[rennis]

I'm new to this type of truck but will add to what others have said:

- I use the Ford branded fuel additive/Cetane Booster.  I don't know if it is necessary but it's inexpensive (4 ounces every refuel) and seems like cheap insurance to me.  I don't see any change in MPG with or without it.  

- I plug the block heater in when it gets down close to freezing and below.  The Ford block heater only needs a couple of hours to get the oil pan up to 80 degrees.  Pretty impressive.  I feel better knowing the engine comes up to temp faster especially on shorter drives

- My truck doesn't use a lot of DEF but I am looking at getting the "platinum" junk going forward - some people think it's worth the extra cost.  See my point above about the cetane booster/cheap insurance argument.

- Dealer does oil changes for me and they use the recommended oil from Ford. 

- Last point:  These things are happier when worked.  A poster above pointed out that if you're not going to tow with it or do HD stuff the diesel might not be the right option.  I agree.  Find a way to use it hard (long road trip with grades and heavy acceleration, etc.) between regular uses on your short-ish commute if you're not doing any towing with it.  These things were built to tow and that is when they're happiest, in my opinion. 

[redrooster]

Follow this guy's advice.  He build engines and each manufacturer has their own flaws. 

 https://youtube.com/shorts/ZAbXvwjhTIo?si=2X8PBbHSkKtOfe3P

[shawndoggy]

21 hours ago, UWSkier said:

FYI, GM doesn't include 12v cigarette lighter sockets on the 2024 trucks.  If you have 12v accessories, you need to find a workaround or install one aftermarket.  That was an unpleasant discovery on my new truck.

curious what you are running?  Seem like most everything has switched over to usb in the last 8 years or so.  All of my vehicles' 12v receptacles have low profile 2 port usb things stuffed in em anyhow.   

[shawndoggy]

2 hours ago, rennis said:

- Last point:  These things are happier when worked.  A poster above pointed out that if you're not going to tow with it or do HD stuff the diesel might not be the right option.  I agree.  Find a way to use it hard (long road trip with grades and heavy acceleration, etc.) between regular uses on your short-ish commute if you're not doing any towing with it.  These things were built to tow and that is when they're happiest, in my opinion. 

Ride quality seems a little better with all 500 lbs of my boat's lead in the bed for the winter too.