Hi everybody

I am all new to this forum and to chevy.
Just picked up a black 04 3500 dually, 2wd, LT with the LLY engine.
Truck has +/- 7000 miles on it

Took it for a (small)trip last weekend and the milage was horrible (I think)

Took it for a 90 miles trip, Driving 75 - 80mph and got 12 - 13 MPG.
The truck runs high RPM's (2400 @ 80mph appr.)
This was on cruise control empty (except a 38lbs dog:), no trailer.

I sold my 01 (ford) excursion (which was a lot heavier). It got 17 - 18 on highway trips.

Basically what my question is:
1)Is this mileage normal.
2) what are the best fuel tanks for in the bes (looked at transferflow)


Thanks for any help

Try same trip at 70 mph. Think mileage really takes a dump higher than that.

I average under the same cicumstances about 14 MPG with a similar truck but with 4WD and 12K miles.

A dually is thirstier than a srw. Mine gets 15 or 16 on the hwyat 65 or 70 mph

Thanks for the info!!


I am now a little scared what will happen with a 40ft enclosed gooseneck:eek: .

I will get used to it. love the truck otherwise.

Sander, it only goes so low. My worst was pulling 14700 open deck over with a tractor averaging 75 sometimes 80 and I still got in the low 11's. That was a total GVWR of like 23,800 or slightly more, 3 adults plus gear and extra fuel. I wasn't being that nice either...it was my 02 CC 2500HD Chevy DMax with about 28K on it. My 05 LLY is getting around 13-15 around town in the hills...I wish for more but the damn foot keeps pressing down to the floor. ):h

I have seen 5.31 mpg with 1 of mine loaded, 13.5 seams to be the average unloaded at 78mph. Some are worse than others, and slowing down will definately help. It seams like 50 is the sweet spot for mileage, but I can't stand to drive that slow.