How Often Should a Generator Be Serviced?
In This Guide
How often should a generator be serviced is a question with two answers, because a generator is measured in both calendar time and running hours, and whichever arrives first is the one that counts. A standby unit that tests weekly but rarely runs for real is on a different clock from a portable that gets hammered through a week-long outage. Here is how to think about both, and what a service actually covers.
The Two Clocks: Hours and Calendar
Every generator ages two ways at once. It accumulates running hours whenever it is actually working, and it ages on the calendar whether it runs or not, because fuel degrades and batteries fade while it sits.
So the rule is always whichever comes first. A generator run hard through outages hits its hour limit quickly. One that mostly sits still hits its calendar limit first, through stale fuel and a tired battery.
Recommended Service Intervals
| Task | Interval |
|---|---|
| First oil change (new unit) | After the first 20 to 30 running hours |
| Oil and filter change | Every 100 hours, or annually |
| Air filter | Check each service, replace annually or as needed |
| Spark plug | Inspect annually, replace per manual |
| Full service (portable) | Once a year at minimum |
| Full service (standby) | Once a year, professional |
| Oil during a long outage | Every 50 to 100 hours of continuous use |
The Outage Oil Change People Forget
Here is the one that catches people out. During a multi-day outage, a generator may run almost continuously, and running hours pile up fast. Two or three days of continuous running can pass 50 hours easily.
That means a generator worked hard through a long outage may genuinely need an oil change during or right after that outage, not at its next annual date. Fresh oil under heavy load is what keeps the engine alive.
What a Service Includes
- Oil and oil filter change.
- Air filter inspection, cleaned or replaced.
- Spark plug inspection and replacement if needed.
- Fuel system check, and fresh fuel or stabiliser.
- Battery test on electric-start and standby units.
- A run under load to confirm it performs.
- On standby units, a check of the transfer switch and controller.
Standby Units Need a Bit More
A standby generator is a permanent installation wired into the home, so its annual service is broader. Beyond the engine work, it covers the automatic transfer switch, the controller and its self-test, and the battery that has to start it unattended. Expect roughly 150 to 300 dollars a year for a professional standby service.
Why the Interval Is Not Optional
It is tempting to skip servicing a machine that mostly sits unused, but that is precisely the machine most likely to fail when called on. The whole point of a generator is to work on the worst day, and a missed service is how a generator quietly becomes unreliable without anyone noticing until the power goes out.
Rather Have a Real Technician Handle It?
A Wildwood technician comes to your home, diagnoses the generator on site, and gets it running, usually in about an hour. More than 10,000 repairs completed since 2019, with flat rates quoted before we arrive so there are no surprises. When you need power back, you need it back now.