Oil life?? Time vs. mileage ....

3,000 miles or 6 months, which ever occurs first is the general rule....especially if the drive is 30 minutes or less each time.
It takes 20 minutes at operating temp for the engine to start getting rid of the condensation of the night before, and the combustion stuff from the day before from the oil.
If the daily drive is more like 1 hour or more, then it can be stretched out to 6,000 mile intervals.....but still 6 months.