Keith

When accelerating don't let it climb past 2000 RPM. It gets me 16 in the city and almost 21 on the freeway. Even that is with some full throttle acceleration. oh yeah if you do it that way you can leave it in OD and it will be fine, works for me.

Serial Thriller

I realize that and agree with the logic, but I've read of this with other vehicles though I'm not sure it works with our trucks.
The thinking is that you're not lugging the motor as much. For example, I've heard of guys getting better mileage in 6-speed F-bodies by switching from 3.42s to 3.73s, because cruising at ~idle rpm makes the motor work hard, and raising that a little bit helps. I hope I explained that somewhat correctly.

sleepersilverado

iTrader: (1)

well stop wineing i get between 10-13mpg. yall are complaining about it now wait till those of you that are building motors get them in and see the gas mileage. any ways an old guy from louisiana who traveled alot told me he raised his 2 mpg by leaving the tail gate down. of coarse this would mainly only help on the high way.

also arent you suppost to get better mielage with higher octane gas?

Chingon

iTrader: (1)

Yea, I actually experimented with the tailgate up and down on the highway. I got about 2.5 MPG more with it down than with it up...on the highway. On the streets it didn't really matter.

Slowverado

a 6 speed is a DOUBLE OVERDRIVE transmission...our's isn't, plus they weight close to 1000# less than some of these trucks, and have more power to push less weight

David Cairns

I didn't by a 6.0L and a supercharger to save gas...

YellowChevy4.8

iTrader: (36)

i think that is true. although i cant prove it cuz i have calculated the difference, in mileage from 87 octane to 93 octane. I do know that i can get more miles to the tank with 93, but other factors may have a play in that too. I average around 325-350 miles per tank. It was closer to 400-415 with the 16s and 3.42s. But I wouldnt trade it for the extra power and umph I got

onyx

wow, thats not bad... do you think the altitude is messin with my mileage as well as my 1/4 times...?

EVIL

2500hd 6.0 with 4.10's.....i have never seen a gas gauge move so fast!

i would be thrilled if i got 16mpg in mine, with 87 octane at 1.68 a gallon, its almost 45 bucks to fill up once a week!

72firebird

My dad did an experiment with his 6.0L and he found when running 87 octane he got about 15 mpg on the highway but when running medium grade (not sure of the octane) he was getting up to 17 mpg. COnsidering the fact that there isn't much of a price difference it made it worht it to drive it on the higher octane.