May be a stupid question but how does one keep an accurate count of engine hour on edgers, trimmers and the like. Just bought a new trimmer and thought I'd actually read the owners manual for once. To my surprise Kawasaki wants your to do this thank called "Periodic Maintenance" at hourly intervals. Thought of keeping a running log an just estimating the hour of use but that seamed a little to time consuming. Perhaps a hour per tank estimate, determine how many hours one tank of gas will last then simply keep track of the number of tanks used to determine engine hours?