Could anyone tell me if the "Oil Change Required" indicator is tied to a timer or a sensor? I suspect it is a timer based on mileage rather than a sensor. I have spectrometal analysis conducted for my truck's diesel engine, transmission, transfer case, coolant, etc. I haven't had this performed for the minivan as it seemed unnecessary as it is so inexpensive to get the oil changed in a passenger vehicle compared to a commercial truck. If it is a sensor, could you tell me what it measures? Particulate count/density, additive concentration, wear-metal density, viscosity change...

Thanks!

2008 Chrysler Town & Country Limited
4.0L engine

 

...just because I see that I omitted this in the original post...

I know how to "reset" the indicator. It is covered in the Owner's Manual as well as in other online forums. I have reset the indicator before:
Key On, Engine Off
Depress throttle to floor 3 times within a 10 second window
Key Off

Just to be absolutely clear - I am trying to find out if this "Oil Life" indicator is a SENSOR or a TIMER and its associated unit of measure (i.e., SENSOR and a meaure of particulate density in ppm of soot/insoluables triggered at x.xx%, SENSOR and a measure of aluminum wear-metals in ppm triggered at xx, TIMER and a measure of mileage triggered at 2,500-miles, TIMER and a measure of months triggered at 3 months, etc.).

Thanks again!