The oil life monitor considers several factors, other than just miles. For instance, engine temperature, load and towing. If it has been more than 5,000 miles since the last change, I would go with the monitor. The monitor also needs to be reset at each oil change. Sometimes it does not get reset during the oil change and it comes on when the normal interval would have expired. If it has been less than 3,000 miles since the last change, this is more likely. You can reset the light by turning the key to on, without starting and push the accelerator to the floor three times within five seconds.