Tow Mode, when to use it

[fourtenposi]

Under what conditions should I be using tow mode. I pull a 8500 pound enclosed trailer and the truck seems to get better fuel economy when tow mode is off especially when in some traffic.95 degrees out side tranny temp never got above 190. Can I hurt anything not using it? I read somewhere but can't find it now that is was more designed for trailers of 10000 pounds. I would definitely be using it if I was going though mountainous road for the engine breaking.
thanks

[Paul Clancy]

With that trailer I'd be using it every tow. I'm sure the few cents you save on fuel would quickly be offset by the extra wear on brakes and tranny. I'm a long term owner, not leaser, so thats my opinion. I find I get far better control in traffic with t/h (tap the brakes to downshift-slow the rig). I say if you tow it's t/h on...at least with a d/a truck. Something else may be different.