Does your car have an oil service indicator?
Got one on my daily driver HHR when it hits 30% life left, i change the oil. I kinda like them. If you beat on the car the percentage drops quickly, if you drive it easy the percentage drops slower. My wifes grand caravan just says change oil on the odometer when due. I like the setup in the HHR better i can scroll thru the menu and it tells me life percentage of oil, actual tire pressure of each tire, engine actual temp, ave mpg, instant mpg, and 2 trip odometers. Nice setup. I wish the caravan was like that. Oh well you cant have everything. With it being there, i use it. I have almost 100k on the HHR and its ecotec 2.2 still runs like a swiss watch.