You could invest in an oil analysis kit and send in a sample every 3K miles. When it says you need to change then change. Millage is not a good indicator of when to change the oil! In the 1950's, auto manufacturers/Dealers decided that oil changes at 3K miles would not hurt anything, and would help the dealers to make money. While in warranty follow the recommended change interval, to avoid any problems in case of a major engine failure! After that, you should test the oil to determine when best to change it! In any case I would not go over a year without changing the oil!