we just got this car maybe 3 months ago, i changed the oil as soon as i got it, full synthetic 5-30w i think was what i put in it (i got the bottle in my shed so i can check again later). so today we were leaving walmart, i started it up and the change engine oil light came on but the oil is only maybe 2months old. so whats going on?? does the computer just go off of how many miles its been drivin or????