I've now heard so many different answers to this question. Most tell me 5kto 6k on synthetic. When I bought my Renegade, the Jeep dealership say, "Oh these are good for 10k between oil changes!". Which i was highly skeptical of. others have said they wait till 7k. I got my first oil change at 6k, just to be safe.
As far as i know, the Renagde comes with an OLM (oil life monitor). The OLM is flexible and takes various factors into account to make a good guess at oil condition. For example, miles driven, fuel consumed, and things like number of start-ups, RPM and oil temperatures may be included in determining oil condition and projecting when the next oil change is due.
In general I would trust the OLM. If I were uncertain, I would have an UOA (used oil analysis performed (for example at Blackstone or Caterpillar). This will show oil condition and also abnormal wear, if there is any.
How long oil may be used depends on many factors: driving style, severe driving/towing/off-roading, dust, distance and amount of fuel burnt. Mythic oil can generally go at least 7,500 miles (10 000 km) or more. In my current car, I can easily got 10-12k miles, although the manufacturer specs 7,5000 mi oil change intervals. I confirmed this via repeated UOAs.
During the warranty period one should stick to the factory-recommended oil change interval to maintain coverage. Once the warranty is over, one may experiment for freely. I certainly do that.
So, if the vehicle has an OLM, go by that. If the car has no OLM, go by what the manual says. Likely the manual lists a normal oil change interval, for example every 7,500 miles or once a year, whichever occurs first, and it will give a shorter interval for "severe service" (towing, off-roading, racing, dusty environment).
A dealer may want to talk you into more frequent oil changes, because they want to make a profit. That's fine if you don't mind wasting resources and money, but your engine won't benefit from it.