engine oils should be changed ever 3K to 5K miles depending on the type of oil and year of car.
The old vehicles should be changed more often because technology has changed a lot in the past 10 years.
Oil breaks down even when the vehicle is not being used. An acid is formed in the oil during this time and will eat your engine (As me how I know?) causing minute pin holes in the engine block and oil seepage.
To be on the safe side, change the oil as soon as you can. Do not let it go excessively past the mileage or date.