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Posted

Just purchased this truck after 14 years of ownership of my 2003 Duramax. I kind of figured that my fuel economy wasnt going to be as good, and having owned a 2002 1500HD with the 6.0 motor that had pathetic fuel economy, i was hoping that in 15 years they had improved the fuel economy a bit. Doesnt seem like it right now as im lucky to get 14mpg or so on the interstate and 12 around town.

 

Granted, ive literally only had this truck for 2 days and only have 220 miles on it and its not even broken in yet, BUT, here is my question (since ive only dealt with my Duramax for 14 years), what can i do (relatively inexpensively) to improve fuel economy on this 6.0 motor'd truck? Ive been out of the "gas" world and have no idea what theyre doing to gas trucks these days to improve gas mileage.

 

Oh, and for the record, this is the 6.0 FLEX fuel motor. And i doubt i'll be running much E85 thru it.

Posted

MPG will start slowly coming up after break in. I started noticing the engine working better at around 3200 miles. Staying below 70 on the interstate should net close to 15.5 to 16.5 mpg if your careful. I don't know of any modifications that would improve mpg, really just driving technique. I tried a k&n filter, it did help with down low power but nothing substantial and mpg suffered also drivability suffered. It seemed to confuse the shift logic, I'd get hard shifts when I shouldn't of been. Put the stock filter back in everything went back to normal, not going to use anything but paper filters on this truck.

 

I got a 16.3 average over 400 miles on the interstate trips between Houston and Austin. Using cruise control, staying below 70 as much as possible, and using the brakes as little as possible all help. I basically have to re learn how to drive, you become more of an 18 wheeler driver than a pickup driver with the 6.0 if you want some efficiency.

  • Like 5
Posted

I basically have to re learn how to drive, you become more of an 18 wheeler driver than a pickup driver with the 6.0 if you want some efficiency.

 

Same could be said of any engine/truck. Driving behavior is the biggest factor in MPG.

 

Due to EPA regulations (or whatever gov't agency) the auto manufacturers are forced to maximize efficiency of new vehicles. Not much you can do to improve anything more.

Posted

I get 8-12 in mixed driving in town.. Over half the time pulling 8,000 pounds..

Posted

LoL!! well, you guys pretty much stated what i already had a gut feeling of. They havent changed this motor and its efficiency since i owned one back in 2002. Only difference is the driver. I dont get in a big hurry anymore these days (56 years old) and just retired from my hobby of 15 years of roadracing "them damn crotch rockets", so i had my share of high speeds and it just doesnt do anything for me to do it on a public road anymore so i pretty much stay at or just a tick over the speed limit and when towing my 7500# RV, i stay right at the speed limit.

 

I wasnt sure if a cold air intake, or maybe a programmer would do anything for these engines or not. I know a programmer did WONDERS for my Duramax, almost doubled my MPG and the torque and HP was WAY better than stock.

 

I'm still glad i went with the gasser tho. When i bought my D'Max, diesel fuel was almost .50/gallon cheaper than regular gas and i doubled my MPG over the 6.0 i had before. Of course, i was traveling all over the SE pulling a big race trailer and it made sense. These days, i pull this RV 6-8 times a year and a bass boat a few times a year. I just like the towing capacity of the 2500's over the 1500's is the reason i went with this particular truck. Well, that and the fact i couldnt FIND a damn 1500 in the LT version, they all were the LTZ's which were about 10K more than i gave for this one. Guess i'll just baby it a little more than i would normally and leave it alone.

 

Thanks for the feedback!

  • Like 2
Posted

LoL!! well, you guys pretty much stated what i already had a gut feeling of. They havent changed this motor and its efficiency since i owned one back in 2002. Only difference is the driver. I dont get in a big hurry anymore these days (56 years old) and just retired from my hobby of 15 years of roadracing "them damn crotch rockets", so i had my share of high speeds and it just doesnt do anything for me to do it on a public road anymore so i pretty much stay at or just a tick over the speed limit and when towing my 7500# RV, i stay right at the speed limit.

 

I wasnt sure if a cold air intake, or maybe a programmer would do anything for these engines or not. I know a programmer did WONDERS for my Duramax, almost doubled my MPG and the torque and HP was WAY better than stock.

 

I'm still glad i went with the gasser tho. When i bought my D'Max, diesel fuel was almost .50/gallon cheaper than regular gas and i doubled my MPG over the 6.0 i had before. Of course, i was traveling all over the SE pulling a big race trailer and it made sense. These days, i pull this RV 6-8 times a year and a bass boat a few times a year. I just like the towing capacity of the 2500's over the 1500's is the reason i went with this particular truck. Well, that and the fact i couldnt FIND a damn 1500 in the LT version, they all were the LTZ's which were about 10K more than i gave for this one. Guess i'll just baby it a little more than i would normally and leave it alone.

 

Thanks for the feedback!

 

Don't waste your money on a programmer "box tune" for a gas truck... YES, They do help diesels... Custom tune helped out my 6.0 power and shifting performance big time.. Similar mileage because i'm always in the gas. Yet to cruise on the highway with it.

Posted (edited)

Just purchased this truck after 14 years of ownership of my 2003 Duramax. I kind of figured that my fuel economy wasnt going to be as good, and having owned a 2002 1500HD with the 6.0 motor that had pathetic fuel economy, i was hoping that in 15 years they had improved the fuel economy a bit. Doesnt seem like it right now as im lucky to get 14mpg or so on the interstate and 12 around town.

 

Granted, ive literally only had this truck for 2 days and only have 220 miles on it and its not even broken in yet, BUT, here is my question (since ive only dealt with my Duramax for 14 years), what can i do (relatively inexpensively) to improve fuel economy on this 6.0 motor'd truck? Ive been out of the "gas" world and have no idea what theyre doing to gas trucks these days to improve gas mileage.

 

Oh, and for the record, this is the 6.0 FLEX fuel motor. And i doubt i'll be running much E85 thru it.

Congrad on the new truck, There good solid truck. Mine has pulled whatever I needed.

Edited by crankman
  • Like 1
Posted

curious how much you spent in repairs on the duramax over the years you owned it, and how many miles? the 6.0 saves you money in up-front cost and typically cheaper repair bills, you spend your money at the gas station instead of at the dealer or a repair shop.

  • Like 1
Posted (edited)

I also have the flex 6.0 in a '17 2500. With 3400 miles on the truck now my lifetime average is 13.5 (hand calculated but the DIC shows the same numbers). Normal driving for me is about 35 miles of highway at 70mph with 10 miles or so in city traffic. On highway trips I've seen as high as 17.5 when driving 55-65 through rolling/mountanious terrain. I expect better once long haul, at least until I hitch the trailer on. :)

Edited by Dale L
  • Like 2
Posted

I gave up a 2002 2500hd for my 16' it's not true there are no improvements

  • Like 1
Posted

curious how much you spent in repairs on the duramax over the years you owned it, and how many miles? the 6.0 saves you money in up-front cost and typically cheaper repair bills, you spend your money at the gas station instead of at the dealer or a repair shop.

Well, $5K just 2 years ago on injectors (that needs to be done every 135-150K), this was my second set, first were replaced under warranty at 88K. I'd say since ive owned it, not counting the injectors, ive spent every bit of $6K or more on repairs. The dmax is a GREAT truck, hell, i LOVED that truck, and it didnt "break" often, but when it did, it was "diesel" schitt, and it was EXPENSIVE, hell, the lift pump and fuel control module was a $1500 repair bill alone. None of those repairs are anything "maintenance" items, even just oil changes are almost double what they are on a gasser, and with todays diesels, i dont EVEN wanna fool with that friggin DEF crap.

 

This truck just makes more sense for me. It was over $20K less than what a Dmax would have cost, and that would take a HELL of a long time to make up on fuel savings, especially with diesel being more expensive than regular now. It was a no brainer when i was pulling a 5th wheel 20K miles a year all over the SE United States roadracing motorcycles, but now all i pull is a 10K pound trailer (thats loaded with all gear and golf cart) about 7-8 times a year. After the last injector change on the DMax, i was only getting around 18 on the hwy and 14-15 to and from work everyday, so even tho this truck def isnt going to get the quite as good a fuel economy as my dmax, it is something i can live with. Week to week it will cost a bit more, but i think over the long run, i'll be saving money.

 

Oh, and when i traded it, the rear in would NOT have gotten me home from Tennessee, and would have been another $1500-2000 repair bill at an out of town dealership, hence the REASON i traded it THIS weekend rather than when i got home. Had i been home, i'd have torn it apart myself to see if i could have repaired it cheaper, but i have a feeling it would have been a catastrophic failure leaving me stranded on the interstate, so it was traded on this.

  • Like 1

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