So my 02 ranger is my first truck with an auto tranny. Ive always had a stick, and Im just wondering if i need to pull with the od off or should I just turn it off on bigger hills? also is it ok to just turn the od off when going about 65 mph and approaching a large hill to get alittle extra grunt? I was pulling about a 2700lb trailer this weekend and on flat ground it seemed fine with the od on and I would just click it off when if start a big hill. is this bad for the truck?

 

when i need passing power on the interstate and i feel lazy , i turn it off ,
for hills ...if your going up a hill and your rpm's are low you can tap your brake pedal "just little for your tail lights come on " and that will shoot your rpm's up .

 

It is OK to tow in OD (5th gear) and may give a fuel economy benefit, especially on the flat or with a light-to-moderate trailer load. Sometimes, 5-4-5 shift hunting can become bothersome during highway towing and the OD can be canceled to stop it. OD Cancel can also be useful for engine braking downhill because it locks out 5th and engages the coast clutch in 4th.

The transmission shift schedule is optimized for best fuel economy. Overdrive can be manually canceled at any time or at any road speed but usually costs fuel economy at highway speeds. Obviously, if the transmission was going to downshift from 5th to 4th anyway for a hill or headwind, canceling the OD yourself isn't going to make much FE difference.

I would definitely install a transmission temperature gauge for any towing or heavy hauling. The higher the temp, the shorter the life of the fluid and, ultimately, the transmission. Allowing the transmission to hunt continuously between gears or running with the torque converter unlocked for long periods raises the fluid temperature. The temp gauge lets you know about that so you can change to OD Cancel or making other driving adjustments when/if necessary.