Hi Charrlie_S,
As Dana indicated above, you would need to turn the O/D off when towing, and therefore would not get any additional gas mileage from the O/D when towing. Also, you could lose some gas mileage when towing due to the additional weight from the O/D. Trust me, when I repeat Dana's comments that the O/D must be off when towing. I made a $2800 mistake by towing our tent-trailer behind our Durango with the O/D on. The A518 had to be completely rebuilt. The torque converter came apart into many tiny particles that were scattered throughout the transmission.
Travis
