I use only Castrol Syntec 5w30 or better ones...

I change every 5000 to 7000 miles.

When I first got my car, I changed the oil at 1500 miles at very first time, and then I changed every 3000~5000 miles..

and since I started use the Syntec oils, I change every 5000~7000 miles.

however, I always check my oil level... especially after a racing or a some kind of long road trip.