As far as I’m concerned, the oil life monitoring system in my Honda works perfectly.
This Edmunds article talks about a 2007 Honda whose oil life monitoring system said to change the oil at 5,500 miles. In this example, the car was driving in city-like conditions.
However, the same car (and thus the same oil life monitoring system) told the driver to change oil at 7,600 miles. In this scenario, the car was driving in highway-like conditions.
What does this prove? It proves how effectively the system detects different driving conditions.
In addition, Edmunds took a sample of the changed oil and sent it to Blackstone Laboratories. What they found was that the chemical of the oil had at least 2,000 miles of life left in it. This examples shows the conservative nature of the oil life monitoring system, which urge you to change the oil long before the oil’s life has gone. As another example, a 2008 Pontiac G8 GT that had gone 13,000 miles “before the monitoring system indicated the need for an oil change”, still had 2,000 miles of chemical life left when tested.
So in a nutshell, you can definitely trust your oil life monitoring system, but you should’t stop manually checking either.