Chevrolet Repair: Which gear?, chevy blazer, gm car

Question
K, here is a dumb question, but I just bought a Chevy Blazer and it's my first GM car...There are 2 D's one with the circle and one without....which one should I use for normal driving...I think the one with the circle means OD right? but in my old car they called that disabling the 4th gear and my friend says OD in a chevy makes the rpms drop? so that is my dumb ques D with the circle or D without....thanks

Answer
D with the circle is overdrive. Overdrive does lower the RPM's, because it is a higher gear, kinda like fourth.
Normally, just put the car in overdrive, and it will select the gear that is correct.
If you are driving in the mountains, or hauling a heavy load that seems to cause the transmission to shift real often, like once per mile, then shift it to the D without the circle. The shifting is the problem, cause that is where most auto transmission wear comes from, so you just don't want it to keep shifting up, then very soon shifting down, then shifting up, etc.
So I would say for your normal driving, select the D with the circle around it.
Van