An article in Consumer Reports a year or so ago stated that todays oils are so good that you needn't change them any more often than 7500 miles. I think that's why a lot of manufacturers have changed their tunes in recent years. I'm old school too...used to do it every 3000 miles. But heck, if I can more than double that number, why not?? I've never tried the synthetics....but have read a lot of good stuff about them. I don't see how they could do any harm, tho.