Generator Maintenance: Keep It Starting
How to maintain a generator so it starts when you need it — oil, filters, fuel, the battery and exercise cycles for both portable and standby units, with a simple schedule.
A generator only earns its keep if it starts when the power goes out — and the number-one reason one doesn’t is skipped maintenance, usually stale fuel or a dead battery. The good news: a few simple habits keep both portable and standby units reliable for years. Here’s the schedule.
Generator maintenance schedule
| Task | How often |
|---|---|
| Run under a light load (exercise) | Every 1–2 months (standby self-exercises weekly) |
| Oil change | First ~25 hrs (new portable), then every 50–100 hrs or yearly |
| Air filter | Check each use; replace yearly |
| Spark plug | Yearly or every ~100 hrs |
| Fuel (gas) | Use stabilizer; rotate every few months, or store propane |
| Battery (standby) | Check twice a year; replace every ~3 years |
| Professional service (standby) | Yearly or every ~200 hrs |
The three things that cause no-starts
- Stale fuel. Old gasoline gums up the carburetor. Use fuel stabilizer, rotate the fuel, or run on propane, which doesn’t go stale.
- Dead battery. On a standby, a weak battery is the top failure — check it twice a year.
- Old oil / no exercise. Change the oil on schedule and run the unit briefly every month or two so it’s ready.
Getting ready for storm season specifically? Follow the storm preparation checklist. Not bought yet? Size one with the sizing calculator and compare portable and standby options.
Follow your generator’s owner manual for exact intervals and oil type. Never refuel or service a hot, running generator, and never run one indoors or in a garage.
Frequently asked questions
How often should you service a generator?
Change the oil after the first ~25 hours on a new portable, then every 50–100 run hours or annually, whichever comes first. Replace the air filter and spark plug yearly, check the battery on a standby unit twice a year, and have a standby generator professionally serviced once a year or every ~200 hours. Run any generator briefly every month or two so it’s ready when you need it.
How do I keep a generator ready for an outage?
Keep fresh, stabilized fuel (or store propane, which doesn’t go stale), run the unit under a small load for 15–20 minutes every month or two, keep the oil topped up and clean, and make sure the battery on a standby is charged. Store a portable dry and covered with fuel stabilized or drained. A standby generator does its own weekly self-exercise cycle — just don’t disable it.
What happens if you don’t maintain a generator?
The most common failure is a no-start during an outage — usually from stale fuel gumming the carburetor, a dead battery, or old oil. Skipped maintenance also shortens engine life and can void the warranty. A few simple habits — fresh fuel, regular oil changes, an occasional run, and a charged battery — are what keep a generator dependable when the power actually goes out.