Interval depends on driving habits. Driving on the highway, your car gets fully up to operating temp. before the engine is shut off, so condensation and other gunk is burned off, keeping the oil more clean. For you 5k should be no sweat. In fact, in your situation I'd say it's wasting money to change at 3k. Stop and go driving, or getting in and driving only a few miles then shutting off the engine makes things dirty quicker.

Inspect the old oil when you are changing, to see how it looks. That will tell you more than anything. Heck, Honda suggests 10k on my Accord, and 5k for severe conditions.