just read on another post that a guy heard to not drive in overdrive unless over 40 mph, or its harder on the tranny, is this true?

 

truly, its not harder on the trans. Its more or less harder on the motor as the rpms drop more in higher gears. This puts more stress on the motor. I myself use "D" when i'm doing below 45. Thats just my $.02.

 

I heard something similar. It kinda of makes sense especially in city driving where you make a lot stops, and 4th gear downshifts and upshifts a lot in an automatic. But then again, that what the car is made to do and work in this application.

I know my car manuel says to drive in overdrive then if i want more pulling or stoping power to drive in D.

I think if you driving normal the tranny will last a long time. It you drive your car hard theirs more of a chance the tranny could give regardless in what gear you drive in.

Sorry im not more help. But I normally drive in overdrive, theirs times I'll drive in D, or even 2nd gear to get some very quick response from the car. Just remember to watch the rpm with driving in a lower gear.

 

i think i heard that in cars without automatic overdrive, having it in OD and going at a slower speed makes the pressure of the transmission fluid lower.

 

So then having motor in higher rpms is better for the motor?

 

i drive in [D] and i am happy with my 4th gear, i love my milage... 45k and i have been diong it every time i drive... it is fine...

 

I use OD all the time, it was made there for a reason. I'm assuming you are refering to the person who got his transmission rebuilt and was told not to drive in OD unless over 40. That isn't true. If it was not made to go into OD under 40mph, they would not have programmed it into the computer that way.

 

With your typical stock R4 Auto if you leave it in OD and drive under 40MPH its really in D. It just shifts into OD over 40MPH. So just drive in OD unless you want the extra power from the lower gears 1 2 D. Thats why its called a Automatic.

 

Not that I am an expert, but I just had my tranny rebuilt. It is better to have firm shifts and not so smooth. Driving in D (depending on your gears) until about 45 will allow the tranny to shift into gear. If you leave it in OD, it wants to slip into gear.
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I'm not an expert, but i did stay at a Holiday Inn Express last night. It's an automatic. If there is any difference in transmission life between D and [D] it is negligible at best. I think automakers (in general, not just GM) know what they're doing when they designed these overdrive trannies and i for one have never read or heard of a car manual that says to keep it in D unless you're over xx MPH.

 

Depending on the traffic situation, I'll often drive in 3rd gear as opposed to 4th ..... not so much with 4.10's in the car, but quite often with 2.73's. It's annoying and unnecessary for the tranny to be up and down constantly in and out of 4th gear. In those cases, or in heavy traffic, I'll always put it in 3rd and leave it there 'til I can cruise more steadily in 4th.

...however, I also drive the hell out of my car, so I'll let you all know when I finally cook the tranny!!