been doing this since I've had this car over a year ago. How many other switch from drive to overdrive when traveling faster than 55mph?

I don't even know why I do it, perhaps it saves a little gas? Anyway; who else finds themselves shifting and downshifting on the regular.

I always put the car into drive when i start the car, I always then switch then to OD if i know im going to be going over 50 mph, when the car is in D it prevents the trans from trying to loc the TC

I always use OD. Why would I not? Unless for weather related conditions that I want to go slow.

Drive when I am driving aggressive and overdrive when I am not.

I'm interested in this distinction, too. What'* the difference between usind D or OD? I always use OD, no matter where I go or what I'm doing. What'* the difference, anyway?

I only put it into Drive when i'm hot lapping it somewhere, and want the engine to respond just a lil quicker.

Overdrive is fine for ALL normal driving. The only time where you sholdn't use it is towing.

OD will enable the TCC lockup and 4th gear I believe.

D only goes through the first 3 gears.

Correct me if I'm wrong.

Like Jason explained, OD is fine for normal driving. However, when I want to have some fun, I keep it in D ... actually it'* labeled '3' for me.

you are correct D prevents the trans from locking the TC, and when you are in OD the TcC will lock up when necessary. I like to use D to prevent my TCC locking when driving around the 40-55 mph range, the TCC locks and unlocks too much. I use D to prolong my TCC and prevent early failure

My 98 Monte Carlo had 1st, 2nd, D, and OD. My 02 Bonneville has 1st, 2nd, 3rd, and D. Does that mean that D on the Monte is the same as 3rd on the Bonneville?

Soooooo.......

Keep it in 3rd (D) unless you plan on driving on the highway or interstate, then use D (OD)?

yes for the cars with the 4T60-E the shifter is labeled 1,2,D,OD now for the 4T65-E the shifter is labeled 1,2,3,D