I have a 06 auto vibe and had a question about using the overdrive button to 'downshift' to lower speeds.
For example - turning off OD to slow the car down without braking or in addition to braking (ie: in traffic, sudden stop, speed at or lower than 60km/hr).
Does it harm the transmission to turn off OD in these scenarios or should it only be used when towing?
OD in mostly set it and forget it. About the only time you may want to turn it off, is going down a steep hill and you don't want to overuse your brakes to slow down/stop. In that instance turning off OD would free up some engine braking to help slow down/stop the car. Besides that, again it is really set it and forget it.
In exceptional circumstances like you list it's fine and probably good to do. It's not going to hurt your transmission unless you do it constantly. Some people like to downshift early in sport mode on purpose at every stop to save their brakes. In that case it makes no sense. Over the long haul it will cause more transmission wear and brakes are a lot cheaper than transmissions.
Turning OD off is in essence downshifting one gear. It is fine and is recommended.
Automatic transmissions are great but manually shifting an automatic is perfectly acceptable depending on conditions. Since I tow several trailers I manually select the correct gear many times. No matter how good the computer in a car gets, the computer inside my head is still superior. I choose to select the correct gear for the situation.
I sometimes manually downshift when descending hills or before stopping. I sometimes lock out OD on mountain roads to prevent the constant up/down shifting of a transmission seeking the perfect gear.
NE Ohio - home to the most successful Pontiac drag racing team in history - Bill Knafel's "Tin Indian" and also home to Summit Auto Racing.
2009 Vibe base 1.8L auto towing 2009 Aliner Sport hardsided pop-up