Synthetic fluid does last longer than standard motor oils, but I've found that a lot of car guys change their oil every 3,000 mi when you using non-synthetic. The manual says to have your oil changed every 5,000 mi and that is for standard oil; so I'd say you could go to about 7,000 mi on a high quality synthetic.
But if you are more anal or just like taking that much more care for your auto, like a lot of people on the site, I would change standard oil at 3,000 mi and synthetic at 5,000 mi. In the end, synthetic oil will last longer than standard and allow for longer periods between oil changes.