Typically, a car won't light up the check engine light just to remind you that you need to do an oil change. A lot of cars will illuminate a service engine soon light or a maintenance light (or something similar) as a reminder that you're due for an oil change. Automakers even program these lights to appear after a certain mileage. However, a check engine light can come on if your car finds that an oil change is desperately needed. This is the case if you're long overdue for an oil change, for example. Or, if you're running the wrong type of oil in your car. Alternatively, it would also light up if there are problems with the oiling system itself. For instance, if there's a lot of oily sludge building up and clogging the oiling passageways. Or, if the oil pressure is out of spec.