Quote Originally Posted by s_quilicot View Post
overdrive is used on highspeeds. parang ito yung nag enable and mag disable ng 4th gear or last gear sa mga AT.

dapat ang overdrive or OD is laging naka on para tipid sa gas.

IMO OD has noting to do with engine breaking. sobrang bilis naman kung engine break ng 3rd gear.

:peace:
You are right to an extent that it saves fuel because OD is the the highest gear available. But going up hill you need to turn it of so that your tranny will not shift to the highest gear and cause it to overheat. If OD is off then it can only shift to third or fourth depending on your tranny configuration and still be in a 1:1 ratio as opposed to a .XX:1 ratio.

Quote Originally Posted by Gumusut_Amige View Post
climbing steep roads? D has enough power unless you're starting from a complete stop to climb a steep road. btw, steep roads for me is incline more than 30 degrees. barely use 2 and L but 3 yes for engine braking during downhill driving and sometimes during uphill overtaking .
It's not a matter of how much power but how that power in converted to forward movement. Would the vehicle have an easier time going up the incline with the lower gear or the higher gear? If you leave it on D with the OD on it can overheat the transmission. The best thing to do is know the gear ratios of your transmission and the max speed each gear can hold. I wouldn't go up a steep incline and leave it on D if my car is struggling to go up because it shifts up to a higher gear. As an example my truck has the following ratio 3.842, 2.353, 1.529, 1, .839 going up a hil I turn off OD to get a 1:1 ratio as opposed to a .839:1 to preserve my transmission. It must work since I've never had a transmission go bad in 5 AT vehicles except on the used car I bought which already had a bad transmission.