This picture doesn't really need much words. This is what happens when you don't change your oil for 60,000 miles. This is from a 2004 BMW engine. As you can imagine it does not bode well for the life of your engine.

Change your oil every 3000 or every three months which ever comes first. If you use synthetic oil then the intervals are for 7500 miles. A full synthetic does not break down and with vehicle's that get a lot of miles put on them we recommend the full synthetic.