I just wanted to know if O/D used more gas when it's on.

 

no you use less gas with o/d on if its off then your rpms are higher and you use more gas

 

You need to read some stickies or go to howstuffworks.com or something and learn how a car works. I'm not here to flame you, I'm warning you to educate yourself before someone else gives you a bunch of crap.

Overdrive is really fourth gear. When you have OD on, the car goes into a taller gear ratio. This means that at any given speed the engine is turning at a lower RPM and is using less fuel. Take a look at your tachometer (RPMs) the next time your driving. When you click the OD button into the ON position above 45mph, you will see your RPMs drop.

By the way, DO NOT turn Overdrive off when you're above 50mph. If you don't know what you're doing you can hurt your transmission. If you don't know how to use your OD on/off button or what it's for, leave your OD in the ON position. It's an automatic transmission, it will do the rest for you.

In a nutshell, leaving Overdrive off will use more fuel. Leaving Overdrive on will use less fuel.

 

That was beautiful. I was going to reply to this topic but you just gave the best O/D explanation i have ever seen. And btw Greenlight, O/D on will give you slightly less acceleration, so for city driving i would recomend keeping O/D off, but for highway its great.

 

I'm speachless...

 

Don't worry--China just revalued their currency. That will make their exports more expensive, enabling us to continue to live beyond our means and not bother with things like education or common sense. I think that was a great question, asking if O/D uses more fuel. There are no wrong answers on this forum. Not many right ones either!!

 

It makes you wonder ..... Well, at least I do ...

 

higher revs= more fuel

 

Really ... I would've never guessed

 

Isn't the overdrive like the 4th gear on the auto?

 

Ding Ding Ding .. we have a winner.

 

ahahahahahhah ur cracking me up brother

 

 

Any year below a 1:1 direct-drive ratio is considering an O/D gear.

 

The 6M in the 5.5 & 6g have 2 OD's... : So much for a "close ratio transmission" marketing ploy ...

 

wow, that's crazy. I've never considered O/D to be something that had to be turned on. The way I've always seen it, O/D is on all the time. When I want to lock myself into 3rd gear, I turn off O/D.

Unless, you're on the freeway trying to catch the sun, O/D's safe to leave off. It's unlikely you'll hit the limit of 3rd gear unless you're racing. but.... the only reason to mess with it is if you want more acceleration at high speeds.

just giving my 2 cents. Was amazed at the opposite direction I have for looking at overdrive.

 

Just for comparison purposes, I have a real-time MPG on my car:

tested at 60mph with cruise control on:

5th gear=33.1mpg
4th gear=28.8mpg
3rd gear=22.8mpg

Both of these were on a flat surface. 4th gear ratio=.94:1 5th gear ratio=.81:1, not a drastic change only a 300-400rpm drop between gears, BUT 3rd ratio is a 1.22:1 and the difference between 3rd and 4th is roughly 1,000rpm at that speed. Not from the same vehicle, but it gives you an idea of how important RPM is to achieve good mpg.

 

Interesting...I wish the maxi had that real time MPG. My cousins Avalon has it, and I love it to death...

 

But why? do you get free gas?

 

5.5gs have it but I think it was calibrated by 2nd graders, because it's always 2-3 mpg's high.

 

very well explained

 

Except the "DO NOT turn Overdrive off when you're above 50mph" part. It does not hurt the transmission. It's just down shifting out of 4th gear.

 

Please lock this thread. I have became stupider from it.

 

you need to go to pep boys and get u some hub caps playa.waaaahaaahaa

 

I believe you are right. Using words like "stupider".....

 

I knew what overdrive did and all, but I did not know that it could damage the tranny if turned off above 50. What is happening that causes damage. I couldnt find direct info online. MaxKlinger or Anyone have the answer?

 

Is stupider a word? I must admit you got me there, I thought there was something wrong with the sentence to begin with, or maybe I am getting stupider.

 

It's alright my friend. The English language is a complicated beast.

 

Nothing will happen, it has a safety interlock that will not let the engine/tranny over-rev, that's the only danger in downshifting at that speed. 3rd will go to ~130mph

 

All I know is that on the new Malibus (Don't worry, I don't own one. Rental) It has shows the fual economy...it's such a lie according to my sister. The tank is larger and she has to refill more often.

 

I disagree. I don't think the OD switch has anything to do with shift points. All the OD switch does is enable/disable 4th gear. That's it.

 

Nah, I spend $60 a week on gas when I drive conservatively. My comment about O/D being safe to leave off had more to do with the poster that said it could be dangerous to turn it off above 50 mph.

Personally, I leave O/D on all the time unless I'm worried that the AT is going to put me in 4th gear when I need the acceleration that's available in 3rd.

 

O ok i gotcha, on long trips ill flip the od off for a few minutes every 100 or 200 miles or so if i remember, i just trun it off for like a minute, but i think it helps to keep the engine from getting to used to running at the same RPM, kinda like a break in thing. I know its weird but i dont think it can hurt.

 

My car needs no break in, I'll be @ 230,000 by tomorrow at this time, and have driven 4+ hours @ a constant RPM ... Some of you guys are

 

I didn't really want to get into it for the sake of simplicity with the guy, since he didn't seem to be that knowledgable about cars or driving.

Let me first clarify myself. Driving at highway speeds with the O/D off will NOT hurt the transmission (it's not the greatest for the engine, but that's a different story). It's the act of turning the O/D off and downshifting where you will put more wear on the trans. Once the shift is complete, it isn't really a big deal.

Under normal conditions, the transmission only handles load in the direction that the engine is driving the wheels. The only downshifting the automatic transmission does is when you're either accelerating (when the engine is driving the system) or when coming to a stop (in which case the revs are low and the transmission is in a semi-neutral state). In other cases, you'd be downshifting when the wheels are driving the engine (engine braking). Typically automatic transmissions don't hold up as well as their manual counterparts to engine braking. They're not designed to handle much load in that direction. I'm not an expert on this, so if somoene can give a better explanation, please do so. I was just thinking: What happens when the torque converter turbine is spinning faster than the pump? Torque converters aren't designed to operate this way; this might happen the transmission is manually downshifted, and I don't know what effects, if any, would occur.

It only gives you better acceleration at speeds above the point at which it would normally shift into 4th (overdrive). Even so, if you need acceleration that much, it will downshift for you if you give it a little nudge. It all depends on where you're driving; if you're going to be doing less than 35mph and traffic is stop and go, then it might be to your advantage to leave it off. If there isn't a lot of traffic, (or hills or other things that would require the trans to shift more) then it's better to just leave the O/D on.

Yeah, they keep falling off. I bought two used OEM replacements at one point, but they faded and peeled and look like crap. So, tired of the damn things, I took them off and refinished the steelies with Rustoleum Semi-Gloss Black.

I don't think anyone makes one that is terribly accurate. The only true way is to fill it up, divide your miles by the number of gallons, and reset your trip odometer every time.

 

i sent a post yesterday, now i cannot find it. i am new to this web site, however i was really looking forward to the advice that you guys were going to give me.

 

THE WHOLE PURPOSE OF OVERDRIVE IS FUEL ECONOMY.....overdrive is and gear ratio below 1:1 (typically 4th gear on a 5spd) .75:1 would be overdrive this means the motor is moving slower than the speed of the car....but thats a little advanced for you

 

Why even bring it up if the theory is too advanced for us?

 

not always true, when your torque converter locks up and makes a 1:1 to your engine, the rpms will be higher. say your going 80mph your rpms are about 2700-2800rpms. tap your brakes lightly, and your rpms will drop about 500 rpms. dropping you back into 4th gear.