So... how did it know? I have about 3700 miles on it so far. It thought I had a free oil change coming, turned out I had three. Not bad.

 

There is a viscosity sensor

 

I wonder if pure synthetics will last longer between oil changes? Anybody have any experience with this?

 

Viscosity sensor or simply tracking intervals between mileage? Our Toyota FJ Cruiser needs reset every 5000 miles on the oil change indicator.

 

Most vehicles use a mathematical formula (algorithm) to estimate when your oil change is due. It tracks starts, stops, temp, speed, time, etc. to determine when to change the oil. It doesn't know if you have dirty or clean oil in your engine.