um... O/D on or off ??

[newroc]

it's my first car, and i know next to nothing about it. Did a search here but could not find a relevant answer.

I got a 99 I4 automatic, 79k miles, 2 months ago, have a question about the overdrive. Here's what I think I know: Cheap cars don't have the O/D button on the side of the transmission stick. When the OD button is not depressed on the stick, the overdrive kicks in when you're at around 40mph, so you're supposed to go smoother and save money on the highway.

But when the O/D button is pressed, you see the light on the dashboard "O/D off", you get more power for your car, at the expense of using more fuel, so pressing the button is recommended only for city driving under 55mph. Is this correct? So anyone who routinely drives city+highway would be pressing that button several times a day for best performance, right? And if they drive exclusively on city streets, they should always have their OD button pressed, and the "O/D off" light on the dashboard should always be lit?

My question is: Is the O/D button like a manual 4th gear for an automatic transmission car? But when I ride in other people's cars I never see them using the OD button since I never see the "O/D off" light on their dashboard. And on more than one occasion, my friends have remarked that I have a "warning light" on my dashboard, and I have to assure them that's normal when I'm city driving.

Granted, my circle of friends are not auto enthusiasts, so they couldn't care less if they have overdrive on or off. So is my above interpretation correct? Sorry for sounding repetitive, but I'm thinking aloud here trying to convince myself that the OD is relevent. And are all you auto affictionados pressing that O/D button as if it were an extra gear shift?

Disclaimer: as I said I know next to nothing about cars, so this is a "um, hello??" kind of question, and I'm not trolling.

[TadS]

Leave the OD on, unless you need the higher revs. Keeping the engine at lower RPM's is better for the parts and for the gas mileage. Generally, some engineer put alot of thought into the ECT on the A140E take advantage on it .

[newroc]

On my particular car, my daily usage is around 5-10 city miles a day, and with the OD on, I have to floor the pedal to move the car out of an intersection, and the revs go through the roof (3-4000s). With OD off, the revs are actually lower, with double the power, does this make sense?

[WhiteSLEV6]

Overdrive should always be on.

The only time I take it off is when i go up a really high road and when I first start the car in the morning but I take it off after like 3 minutes.

And yeah, like you said.. it's like 4th gear for a manual.

btw anyone know the max speed with overdrive off? Ive never really tried it.

[ThatVietGuy]

As far as I've gone is like 90 mph w/out OD.

Alsot, I've heard that it's wise to turn off OD when in traffic so you can prevent the car from constantly shifting between third and fourth.

[DatSRBoi]

Hmm Interesting stuff.

Is it true that you dont need to turn it off in racing since your RPM will go high and shift anyway? I see lots of racers doing it. I personally dont think it does anything..

[ThatVietGuy]

I don't see the point either. It's not like it starts off in fourth gear at a dead stop.

[DatSRBoi]

I don't see the point either. It's not like it starts off in fourth gear at a dead stop.

Thats what I think so too. I think it was meant to keep a car in higher RPM at stable speed. usually in hills to advoid loosing power when gas is release. Or bad weathers too....I think..

[Jon11582]

Just keep OD on all the time.

OD off keeps you out of third gear, so its like you have a 3 gear auto.

If your on a hill, or apply more gas, the tranmission is smart enough to downshift to third to provide more power. And the tranmission shifts fast enough that any extra "control" you get from having OD off isnt really an issue.

The only time it should be off is when your hauling something (need more torque, which more is avaible at higher RPMs), or going downhill. (Youll notice that your engine slows down faster when OD is off since there is more "engine braking" at higher RPMs. This way you can let the engine slow you down, and you dont need to brake all the way down the hill, preventing brakefade..In these areas you usually see signs that say "trucks, use lower gear". )

I dont think the Solara makes a capable hauler, so going downhill should be the only time you would use it, and even then its only to prevent brake fade, and I dont think theres a hill thats long enough in the U.S. to make this a real issue.

I hear that you have a higher max speed in 3rd gear than 4th as well, but I'm talking about everyday driving, not bouncing off the speed governer. I think the OD off button is more of a legacy thing, but with todays "smart" auto transmissions, its not really necessary.

I do use this button quite a bit though...How do I use it? When I see a speedtrap up ahead, I click off OD, and let the engine brake me. If you pass a cop whos on speed patrol while your brake lights are on, its almost a sign that you know you were going too fast.

[WhiteSLEV6]

If you pass a cop whos on speed patrol while your brake lights are on, its almost a sign that you know you were going too fast.

You know how much speed you lose if your going like 50 mph and press the OD button??

[Jon11582]

Try it. You lose alot more speed if you were actually going over the speed limit. (i.e. 80 down to 60).

Note i DONT advocate speeding, but I know it happens from time to time that your over the speed limit without noticing it (of course, because your busy being a safe driver and keeping your eyes on the road.)

[1st Gen Sol]

^^^^ tried it earlier today, po-po on the Southern State Parkway, I was going about 85 turned the OD off and it brought me down to about 67.

.....good looken Jon