in my car it doesnt say "OD Off" unless i turn off overdrive, but i always have overdrive on 100% of the time.
i guess a newer car might turn OD Off if you ARE going uphill, and youre right there at a constant speed right about at that sweet spot where it would normally try and switch gears, to prevent the car being balanced right there for an extended time. but unless you're going up like a ten mile long hill at a constant speed of 35 mph, overdrive should always be on
just leave it on 100% of the time, turning overdrive off will fuck your car engine if you try and hit the freeway doing 65mph in 3rd gear cause your OD is off
and wtf you couldnt figure this out after like four years? lol
Leave overdrive on all the time for normal city and highway driving. You might want to disengage overdrive when going down a long hill to get better engine braking. *LEAVE THE BUTTON ALONE & DON'T FUCK WITH IT*
Turn overdrive off when you tow. Leave it alone, otherwise. You're more likely to overheat when carrying lots of weight or pulling with an engine equipped with overdrive. You won't get "extra engine braking" going downhill. lol You'll just be at a higher RPM and a lower gear, which makes braking easier. Plus, the engine doesn't brake, it just slows down.
Some years ago I bought an '87 Caprice LS from a tow yard. Upon purchasing the vehicle the guy told me "it has a mean overdrive" Now at this time I knew what O/D was, but I really didnt have a clue about a mean O/D. After test driving and eventually buying the car I really grasped what a "mean overdrive" was. The freeway or any long stretch of road is where I'd experience it. Anytime getting onto a freeway pushing the gas pedal 1/2 to 3/4 of the way it would shift through gears 1-3 and hit 4th(O/D) hittin the freeway....just barely keepin up with the flow of traffic. Horrible!! (yes the car was in dire need of a major tune up which came later). Here's the "mean" part. There were 2 ways to get it out of slug mode, 1 was to push the gas pedal ALL THE WAY to the floor and wait about 2 seconds before it downshifted...OR shift it into 3rd myself via the column shift. Muthafucka was slow until I tuned it up though. Memories
O/D is supposed to save you gas in theory. If you drive right it works. You can use it as a means to manipulate the car a bit since you cant "row" the gears. Turn it off on the freeway for a bit, guess what you just downshifted.
Picture it like a 10speed bike and O/D would be the biggest gear on the crank and the smallest gear on the wheel.
In most cars/trucks with manuals O/D is usually the last gear.