How often does oil need topping up?

How often does oil need topping up?
Only when it is down to the add line on the dipstick. On a new car that could be never (oil change time before you need to add), on some trucks I've driven it was daily. Get to know your car, start by check the oil every 1000 miles, if it is all set, move up to 2000 miles, if it is low, top it off and check sooner next time.