|
Generally, the main difference is gas mileage. In the transmission, Overdrive (O/D) is the highest gear. Overdrive allows the engine to have less rpm with higher speed in order to have better fuel efficiency. When you switch it on, you allow the transmission to shift into overdrive mode after the certain speed is reached, depending on the load, it can usually be 30 - 40 mph. When it's off, you limit transmission shifting by its third speed. In my opinion, overdrive should always be on in normal driving conditions.
There are times where you may need to switch it off, such as in mountains areas. For example... the automatic transmission automatically shifts from OD to the 3rd gear when it feel more load and when it feels less load it shifts back to the O/D.
Under certain conditions, such as driving uphill or towing a trailer, the transmission can not decide to stay in OD or to shift into 3rd speed and it starts to shift back and forth. That's the time you may switch it off and help the transmission to decide. You also may need to switch it off when you want to slowdown using the engine braking, for example, driving downhill.
Hope I was helpful.
__________________
The more the members are involved in the process of development, the better we will be as a community of Automobile enthusiasts. Have a suggestion to make the community better, let us know.
Remember, the "No" is always there, you are just looking for the "Yes"
Members please read: Guidelines
|