AT4 6.2L Poor Gas Mileage

[Leevon]

Two things not yet mentioned:  Winter blend gas additives kill mileage.  Also, the truck's engine computer is designed to run richer through an initial period.  You will see and increase in mileage over time. 

Edited January 24, 2020 by Leevon

[brendon444]

On 1/23/2020 at 9:03 PM, Leevon said:

Two things not yet mentioned:  Winter blend gas additives kill mileage.  Also, the truck's engine computer is designed to run richer through an initial period.  You will see and increase in mileage over time. 

Im starting to think the truck may actually be programmed to run rich for initial break in. Truck hit 5000km recently and mileage has started improving.  Right when it hit 5000 i noticed the change so not sure if there is any science to this. 

[Leevon]

On 1/25/2020 at 1:36 AM, brendon444 said:

Im starting to think the truck may actually be programmed to run rich for initial break in. Truck hit 5000km recently and mileage has started improving.  Right when it hit 5000 i noticed the change so not sure if there is any science to this. 

It definitely is, learned this a couple of months ago in a GM powertrain class.   They are programmed this way to allow time for the rings to properly seat and avoid lean conditions. Trainer couldn't tell me if there was an exact mileage, but I've had 3 new GM's in the last 24 months and all of them behaved the same around 3,000 miles where the mileage jumped...which correlates with your 5000km jump.   

Edited January 27, 2020 by Leevon

[Sierra Stan]

Im at 4000 miles with my 2020 AT4 with the 6.2 engine. Running premium fuel and the best i have gotten is 16.4 on a tank. Average so far is 14.6. Rather disappointed.  

[mosby]

 

my '17 denali 6.2 gets around 19 in town, 25+ highway. i installed a magnaflow single with 4" pipes and saw little change.

just got my wife a new at4 6.2 and just was wondering about that. no front air dam like the denali...

[Moose84]

BigEdB

If you are filling up with our Lewis County AM PM trash, I suggest stop that immediately. The Cinex by the jackpot is the best quality fuel for our rigs around. That or the Chevron at 72 because it's Wilcox and Flagel fuel. Other fuels in our area, I have learned, will put a strain on our fuel mileage and also seem to take away from our harsh driving love. I too love to speed. Just giving you some knowledge from our area.