Hi, i would leave it in o/d alll the time, the transmission wont shift into o/d it until speed reaches bout 70kms, so until then the auto will be in third, i dont no why they give you the option to turn it off anyway, its an extra gear to have, the engine works less harder, and you get more out of every gear by having an extra. up a hill the trans will kick down anyway even if the lever is in o/d. you dont have to stop to turn it off just lower the speed to around the sixty mark before you do but. sorry for the long reply hope it helps.