Although it is not a required field, the app uses mileage and hours for several reasons :
To record the sequence of events for your vehicles. Regardless of how much time has passed, the odometer/hourmeter tells how much usage has taken place for the vehicle.
To determine when scheduled maintenance may be due. You can tell when it has been 5,000 miles or 100 hours since your last oil change, or when a valve adjustment is coming due, or when a 60,000 mile service is due.
To determine how much a vehicle has been used during a given time period. The Mileage-Hours report will show elapsed mileage/hours versus a baseline established for the vehicle. This is useful for your own purposes, or even for tax purposes.
Consider using mileage/hours as a way to get the most out of the Motocron application.