im not sure what gear to put my car in i have a 93 chevy lumina with overdrive im not sure if i should put the gear selector over the regular D or if i should put it on the one with the circle around it. and if theres a different time to do each one can you tell me and does anybody now if driving on the one with the cirlce around it is bad for the transmission causing it to slip? thanks alot

Leave it in OD all the time, unless driving in rolling hills and the constant in/out of the overdrive becomes annoying. This is pretty rare.