When To Use Overdrive

[husker]

I have recently purchased a 1998 Lexus ES300 for $9500 from a dealer. It has 125K milage on it. (I am not sure if I overpaid for this car). So far it had a single owner and I am the second owner of this car. It is black in color with tan interior and looks great! The previous owner was taking good care of this car as a baby. It has a feature to switch suspension mode between SPORTY and COMFORT :D. Pretty neat :) I observed that the gear stick has a button for O/D. When I de-activate the O/D an indicator comes up on the dash that says "O/D OFF". I consider this as a warning sign. Can somebody advice me when to use overdrive. I take this car to work and back home all through city with lots of stop lights. Can I engage O/D all the time immaterial, whether I am driving at 20mph in city or 60mph in highway.

Any suggestion would be greatly appreciated.

Thanks in advance :) .

[VGR]

The owners manual covers this subject extensively. The owners manual recommends using overdrive at all times except in certain rather rare situations.

Like if you are driving up a hilly highway in the 30-70 MPH range that causes the transmission to repeatedly shift in and out of overdrive, then the owners manual recommends turning the overdrive OFF and letting the engine run continuously at a comparatively high RPM. Locking out the overdrive in a situation like that saves wear and tear on the transmission and is also less stressful for the engine.

Also, if you are decending a long highway grade in the 30-70 mph range and need to brake frequently to control the car's speed, the owners manual recommends turning the overdrive OFF to let engine braking assist in controlling the car's speed. Locking out the overdrive in a situation like that helps prevent brake overheating which can lead to brake fade and warping of the brake rotors).

[husker]

Thanks for your excellent response. Regarding the reliability of this vehicle, do you or anybody have any comments. As I said before, it has 125K and I paid $9500. It has chrome wheels, Nak audio, 6 CD changer, sport/comfort suspension change, leather, heated seat, black paint (very little blemishes), power window, power moonroof etc., except that the power lock doesn't unlock. I have an appt with the Lexus dealer to diagnose the prob. I am not sure, how much it's going to cost me. Overall, is this vehicle worth for the money I paid. The car looks excellent. No engine noise and vehicle drive like 10K. The owner had serviced the car with the same Lexus dealer since 1998 until Mar 2005 including the oil change. I got the complete service history for this vehicle from the Lexus dealer.