A standby generator can sit silent for most of the year and still need servicing, and it can run hard for a week in a storm and need it far sooner than the calendar suggests. That is why manufacturers write their schedules in engine hours.
Read the hour meter, not the date
Oil changes, filters and plug checks are all set against running hours. A generator that ran for three days during an outage may have used up a year of its interval in one go. The date tells you nothing about that.
Some jobs run on both
Oil degrades even when the engine is idle, and batteries age whether or not they are used. Most schedules want an annual service regardless of hours, so you track both and act on whichever comes due first.
Exercise runs count
Many standby units start themselves every week to keep everything moving. Those short runs add up on the meter, which is one more reason the hours drift away from any schedule you keep in your head.
More than one machine makes it harder
A farm, a site or a business with several generators has a different set of hours on every one. Knowing which unit is closest to its next service is most of the job.
GeneratorLog is an Android app that takes the reading off the hour meter and works out hours since the last oil change and hours left before the next, showing which machine is closest to the line.
