The general guideline
Most manufacturers recommend service roughly once a year, or every 100–200 run hours, whichever comes first. A unit that ran extensively during a real multi-day outage may need service sooner than its annual schedule would otherwise suggest.
What a typical visit covers
A standard service includes oil and filter changes, a battery load test, spark plug or injector inspection depending on the model, and a functional test of the transfer switch — confirming the whole system, not just the engine, is working correctly.
Why the weekly self-test isn't a substitute
Most standby units run a brief automatic self-test weekly, which catches some problems early — but it's not a substitute for hands-on service. A self-test can pass while a battery is quietly degrading toward failure, which is exactly the kind of issue an annual visit is designed to catch.
Adjusting the schedule for climate and use
Units in harsher climates — extreme heat, high humidity, coastal salt air — sometimes benefit from more frequent service than the standard annual baseline, since these conditions accelerate wear on components like the battery and enclosure. A generator that ran extensively during a real multi-day outage is also a good candidate for an out-of-cycle check rather than waiting for its next scheduled visit.
Frequently asked questions
Sources
- NFPA 37 — Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines — Covers clearance, ventilation, and safety requirements for stationary standby generators.