I saw a study that says if you change every 3k it actually increases engine wear. When you drain all the oil out of the engine, on start up after an oil change engine parts run dry for the few moments it takes to get the oil pumping again while the fliter is filling. So the more often you change oil the more of this really bad stress you put on the internals, especially in the top end. It recommended every 7k or switch to synthethic and every 20k.