the reason it's such a long life is because way back in the day, oil used to be dirty, engines had serious blowby and the pcv systems were crap. now, oils have detergents and other chemicals that make them last longer. pcv systems clear out excess fuel in the oil, so yes the oil can last up to 15000 miles in a change.
that old ideology of changing oil every 3000 miles is a waste of money. sure it's easier to change the oil than change an engine, and yes after soo long even new oil will sludge. but it's WAAAY more than just 3-5000 miles. you could safely go 10000 miles as long as you drive easy
also, the service interval is a condition based service. it will change the mileage depending on how and where you drive.