I have the tow package on my 2007 crew cab, and a 5.3 v8.
I am trailering a 21 ft bay boat, on a tandem trailer. I notice when
I engage the tow mechanism, I get about 12-13 mpg.

Someone mentioned that since the boat was not really that heavy,
I should only use D3, and I would get better gas mileage.

Another person said, they would use the tow mechanism, but if
I got on the interstate, once I was up to speed, to engage it back
in drive, and it would not hurt anything, plus the mileage will be
much better. It could only hurt if you slowed way down, or got
off the interstate. What do you guys think? just don't worry about
the gas mileage??

 

Gas engines are severly effected by wieght. Keep the tow engaged, gas is cheaper than a transmition. It will shift to OD at about 65/70 depending on how much drag is recieved from the boat. How much does the load wiegh? (boat w/fuel, trailer, gear, and 3 cases of beer) Gas wieghs ~ 8lbs per gal. Beer is ~ 8.5.

 

definately use tow mode. As cracker said it is much better for the tranny. Also it will keep you from shifting alot. It also seems to pull stronger and shift more predictably. Yes milage decreases, but it is worth it.