I've read a couple of articles and heard a news item on the radio saying the current wisdom among experts is to change your oil every 5,000 miles rather than every 3,000 miles. While this may be true there are at least two things you need to consider. First is the type of driving you do. If you drive your vehicle under difficult conditions you may need to change your oil more frequently than every 5,000 miles.
Second and very important is that if you do not change your oil as per the manufacturer's recommendation you may void your warranty and set yourself up for a very large repair bill. It is safest to change your oil as recommended by the manufacturer.