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?

NO! You have several very serious problems. First of all slow down. By your own admission you are a newbie and yet you are running the maximum speed for (what are probably ST tires). If your transmission is constantly shifting something is very wrong. That repeated shifting is generating excessive heat which is not your friend. If your truck does not display transmission fluid temperature get a Scan Gauge as it is imperative that you know what is happening. Double check with the dealer on the proper operating procedure (O/D, CC Tow Haul etc). When you lock out a gear it has to stay locked out and you should be able to run all day in 6th on the flat.

You should have no, none, zero, nada, sway (ever)! Sway is the rig telling you something is wrong and not in a good way. Sounds like you have plenty of truck so take a hard look at your WDH setup and get the rig to the Cat Scales. Try running at 55- 60 and I think you will find that a lot of your discomfort and problems will disappear (like a fart n the wind). :C