I don't give a shit what your owner's manual, your car dealer, the supposed expert on TV, or anyone else says. CHANGE YOUR OIL AND FILTER EVERY 3000 MILES RELIGIOUSLY! I can't stress this enough. If you do only one thing to your car in the way of maintenance, changing your oil at 3000 mile intervals should be it.
If you're one ofthose who uses synthetic oil (Mobil 1 et. al.), change it every 3000 miles also, even if the manufacturer says 5000 or 7500. Take my word for it, it's worth the price in the long run.
I'll have more oil science later on, along with wisdom about other lubricants. I just can't stress the value of regular oil changes enough. HEED MY DECREE.