98 eclipse rs overdrive?

should overdrive be on or off?

keep it on

on for gas mileage if you want to do highway races turn it off then your car will stay at a higher rpm at cruising speed and wont have to downshift when you floor it

If you are pulling hills and/or shifting often because of terrain, turn it off until you get back on a straight stretch. I can't remember right now, but whatever cools the transmissions turns off in overdrive, so your tranny will gain excessive wear from being hot due to lots of shifting.