Could someone please explain the Overdrive button on an automatic transmission?

Question

I recently bought a new car: an automatic transmission. (2007 Corolla CE.)

1. When should I turn Off the overdrive; when should I keep it On?
2. At what speeds should I turn Off the overdrive; when should I keep it On?
3. On what type of terrain should I turn Off the overdrive; when should I keep it On (flat roads vs hilly)?
4. If I want “to get better gas mileage:” should I turn Off the overdrive; when should I keep it On?
5. If I “don’t want to burn out the transmission within 5,000 miles;” should I turn Off the overdrive; when should I keep it On?
6. Also: I’ve noticed that when I turn off the overdrive the RPMs jump up and when I turn it back on, the RPMs go down. How does this effect gas mileage and the health of the transmission? [Ok that’s the same as 5 & 6]

I have two friends who are trying to be helpful, but together, they have given me conflicting information to the point where I don’t know what to think! Can anyone please explain all this in plain language? :\

Answer 1

Lets assume that ur car is a 4speed auto. If you turn o/d off, that will reduce the gears to a 3speed auto. and the 2 reduce it to 2speed, L means 1speed (1st gear always)
This is how you shift manually which AT.
now, lets start answering ur questions.
1. almost never... probably when you are racing and wants to squeeze all out of ur car.
2. I own an AT corolla as well, the manual saids O/D off can hold up to 70MPH. which means, when you are racing, you have to turn it back on at around 70MPG to go into 4th gear. Or you will end up over rev ur car and blow up the engine.
3. as the 1st question, you almost never have to use it.
4.O/D on for better mileage, since ur have more speed to use in the free way. On stop and go traffic... it doesnt matter....
5. long as you keep the engine below 5K rev almost always, you will not blow anything (exception might apply)
6Duh... like a MT car... when you down shift, the rev goes up to for the engine's rotation to correspond to the wheel's rotation, google up how does gear ratio works if you wants to know more...

Answer 2

Overdrive is just a higher gear. Turning it off just shifts it to a lower gear, just like shifting from drive into 2nd - only using a button instead of the shift lever. Leave it turned on, and the car will be just fine - and give better fuel economy. Only turn it off when driving in really hilly areas - if the transmission needs to shift down to climb each hill while maintaining the same speed (then shifts up again on the downslope), it increases the wear to the transmission. If you have a succession of hills coming, turning it off makes it easier on the trans, as it doesn't have to keep shifting up and down for each hill. This will, however, use a little more gas, so don't bother unless the car needs it. Leaving it turned on the rest of the time will save gas, and won't hurt your engine or transmission at all.

Answer 3

Overdrive in an automatic car adds an extra gear to your tranny enabling you to use different gear ratios and not rev your engine so much. If overdrive is off your car might operate on 4 gears, whereas WITH overdrive you have five. So your car will upshift earlier than with OD off. This means your engine will run quieter and also use less gas.
When on the highway you should DEFINITELY use overdrive. Your car prob cant earch top speeds without it. Drive at 75 with OD off. You will struggle to go faster and the car which rev super high to go faster. But with overdrive it wil be easy and will save you a LOT on gas. DEFINITELY use overdrive on highways.
Most people never turn overdrive off and leave it on whenever they drive. This is OK (I do it too) Just make sure you turn off overdrive when you need extra power, have a lot of weight in the car or are climbing a hill, ect. In heavy stop and go traffic, you may want to turn OD off as well since your tranny will not have to change gears as much.
OD off= steep hilly road, need power to tow cargo, stop and go
OD on= casual driving, highway definite, save gas, achieve top speed, what most people regularly use

Answer 4

Overdrive is what you put your car gear into when you're on the highway and cruising fast, like on flat or downhill. It's basically an extra gear that takes strain off your engine at higher speeds while keeping your car moving. It might help to read your owner's manual on the subject, or ask your dealer mechanic all about it.

Answer 5

YOu should leave the O/D button "on" always, except if you are driving in very hilly terrain (or towing something) where the O/D won;t really work well anyway (it needs to keep downshifting to get up the hills). IN all other cases, just keep the O/D on and forget about it. The car will decide for you, when it needs to shift into overdrive.

Good Luck.

Answer 6

Overdrive is a gear ratio in your car built around the idea of driving your car at a highspeed(ie freeways) at continous momentum so, when you know you will be driving on a freeway at a good constant speed, this when you should have it turned on. For inner city driving, you should leave it off, because it is not built on the idea of slow starting and stopping, and will use your car less efficiently meaning more gas burnout and higher wear on your car

Answer 7

Keep it on. In case you are constantly driving at that speed where the transmission is shifting too much and it becomes annoying, then turn it off that day. You should use it where it feels more comfortable and uses less fuel. Measure it.

Answer 8

Anytime you are in hilly country turn it off. Most of the time have it on
for better gas mileage. Also in snow you may want it off.

Answer 9

Freeways - Yes
City - No
Towing - only if you want your transmission fried. (Personal experience...don't tow any decent weight in over drive)
Gas Mileage - should help if you use it properly... might want to check your owners manual for manufacturer recommendations.