Just completed first tow....good and bad!,

zogg wrote:
As a newby, We just finished our first tow with a 2011 GMC hd 2500 6.0 gas from st louis, mo. to harrington beach campground north of Milwaukee, Ws. Trailer is about 8000 pounds. Trip was about 860 miles round trip.

Truck towed pretty well, but averaged 7.3 mpg....surprised, as I expected about 9-10....ouch.

Transmission in tow/ haul never went into 6th gear, and continually shifted from 5 th to 4 th and back as we went over tiny hills....maintained 65 mph for the whole trip. I tried taking it out of tow/haul, tried cruise control and no cruise control, and nothing seemed to make any difference in the way it shifted. I even tried manual mode in 5th gear but it still greaed down to 4th..

Had a little sway from time to time but nothing awful. The roads north of Milwaukee are awful rough, being concrete with constant ripples....beat me to death and shifted furniture in the trailer....

Does this all sound normal to those who are experienced?

I'm not calling you a liar or anything but I towed a 8000 pound f'ver with a 2004 6.0L/4speed trans 3.73rear up and down the PA turnpike from Pittsburgh to Bedford and never got below 9MPG running 65MPH. I can't believe you can pull on some of the flatest ground in the nation and get better mileage.

So either A: you trailer weighs more than what you say or B: you're going faster than you say.

I held OD except for the mountain grades and mine never hunted. I was even running 265's over the stock 245's