Oil quality tester
 

I have often wondered how the automatic systems calculate when to change oil. Is it based on the number of starts? The number of miles? Or something like this:

Lubricheck will let drivers know when their oil needs changing

There's an algorhythm that uses a number of inputs to calculate the change interval. Sure beats throwing away good oil every 3000 miles.

I've read that the method used varies between the manufacturers and models. Some calculate based on miles driven, length of trips, how hard the car is driven, etc. I've even heard that some can monitor viscosity.

I recently ran a Blackstone sample on my 1yr old, 10,000 mile oil and their recommendation was to go another 2k more. I'll stick to my once a year oil change schedule for all of my petrol engines.