I leave my O/D on just about all the time, except going up OR down steep
grades. I also turn it off for quick high speed passing. We get great gas
mileage, 19 city/ 24 Highway 4.0 SOHC. I have 94,000 on her now. I attribute
this gas mileage to the way I maintain the vehicle and the use of Mobile
one oil.
In occasion I pull our POP UP when I do I seem to be turning off the O/D
more often but you will know when you need that extra torque, you'll just
feel it.

Searcher1