You're correct. Oil monitor is based on mileage, age, and driving habits/conditions and will fluctuate. I do town and city driving and it'll usually blip me around 7-8k which is what I change at. If you tow heavy loads regularly you'll more likely to change around 4-5k (according to the manual also).That is news to me I've watched my oil life fluctuate depending on the amount of wheeling and driving conditions I drive under. I was certain it was monitored to the oil and not just the miles on the odometer.