How Often Should I Service My Whole House Generator?

A home standby generator needs annual maintenance — once per year, every year, no exceptions. That's the baseline cadence. On top of the annual service, certain components need attention on longer intervals (spark plugs every 2-3 years, valve clearance every 2-3 years, battery replacement every 3-5 years).

Skipping annual service is the single biggest predictor of generator failure during real outages. Every annual service we run, about 10-15% of units we open up have something that would have caused failure during the next outage event — old oil with metal particulates, a battery that passes voltage check but fails under starter load, a dirty air filter restricting airflow, a fuel regulator with debris. The annual service catches these.

The annual service schedule

What gets done every 12 months:

Engine maintenance

• Oil drain and replacement (full synthetic or specified weight)
• Oil filter replacement
• Air filter inspection and replacement if needed

Electrical system

• Battery load test (not just voltage check)
• Battery terminals cleaned and treated
• Charger output verification
• Wiring connections checked for tightness

Functional testing

• Manual start and run-up
• Voltage and frequency under no load
• Transfer test (kill grid, verify ATS transfers, verify return-to-grid)
• Self-test schedule verification

Inspection

• Visual leak inspection (oil, fuel, coolant if liquid-cooled)
• Mounting hardware torque
• Enclosure condition
• Pest / mouse inspection (real issue in Northeast Florida)
• Fuel system check

A complete annual service runs 60-90 minutes on-site.

Longer-interval service items

These show up on top of the annual service every 2-3 years:

| Item | Interval | |---|---| | Spark plug replacement | Every 200-400 hours, or every 2-3 years | | Valve clearance check / adjustment | Every 2-3 years | | Coolant replacement (liquid-cooled units only) | Every 3-5 years | | Starter battery replacement | Every 3-5 years | | Fuel regulator service (propane) | Every 5-7 years | | Major service event | Every 7-8 years (mid-life refresh) |

A maintenance plan typically schedules these automatically as they come due.

When during the year to schedule it

For Northeast Florida specifically:

Best time: April-May. Before peak hurricane season starts (June 1). This way:

• Unit is in peak condition for the months it's most likely to be needed
• Service slots are widely available (post-spring is typically lower demand for service)
• You're not competing with post-hurricane backlog
• Battery, oil, and fuel systems are fresh going into the highest-stress period

Worst time: September-November. Post-hurricane queue means service appointments push 4-8 weeks out. If your generator runs hard during a named storm in September, you want to bring forward your annual service to the months following — but most homeowners discover this when scheduling is already backed up.

Acceptable times: December-March. Lower urgency, easier to schedule, no obvious downside. Most homeowners on maintenance plans default to a quarterly cadence (Q1 service, Q3 secondary check, etc.) that fits this rhythm.

We try to schedule new customers' first service for the spring slot when possible — gets the rhythm right from year one.

What "skip a year" actually costs

Three real failure modes from skipped service:

Old oil leading to engine wear. Generators that go 24-36 months between oil changes start showing measurable engine wear. By year 5-6, the unit is running rough and burning oil. Fix: $1,500-$3,000 head/valve service.

Battery dead on the day you need it. Most common "my generator didn't start" cause. A 4-5 year old battery often passes voltage check but fails under starter load. Fix: $150 battery replacement. Cost of not having it: the entire outage during the hurricane.

Fuel regulator gummed up. On propane especially, fuel regulators can stick after years of inactivity. Symptoms: unit starts, runs at light load, hesitates or shuts down at heavy load. Fix: $200-$400 service call. Cost during a real outage: AC drops out at the worst possible time.

The pattern: $300-$400/year of maintenance prevents $1,500-$5,000 in eventual repairs and avoids the worst-case scenario of unit failure during the actual outage event you bought it for.

Before-storm checks (DIY items between services)

Things you can do yourself in the days leading up to a named storm in the Atlantic:

• Visual check the unit's status LEDs — should be green (ready) on most brands
• Run a manual self-test if you know how (button on most units' control panel)
• Check the manufacturer app (Mobile Link, OnCue, etc.) for any pending alerts
• Verify fuel availability — propane tank level should be at least 50% before storm landfall
• Clear any obstructions around the unit (debris, leaves, anything against the air intake)
• Check that nothing has nested in or near the unit since last service

These don't replace annual service, but they catch the most-common pre-storm issues before the unit needs to actually run.

Post-extended-run service

After your generator has run for an extended period (more than 50 hours continuous, or 5+ days during a hurricane outage), bring forward your annual service:

• Oil should be changed within 60 days of the extended run (regardless of when annual service is normally scheduled)
• Battery should be load-tested
• Air filter should be inspected and replaced if needed
• Visual leak inspection (extended runs sometimes loosen seals)

This is the "maintenance you skip at your own risk" item. After Helene (Sep 2024), Idalia (Aug 2023), and Ian (Sep 2022), homeowners who brought forward service had clean year-2 service experiences. Homeowners who waited until next regular schedule discovered worn components on regular service.

Bottom line

Once a year, every year. April or May. About 60-90 minutes of service work, $300-$400. After hurricane season runs, bring forward the next service. Skipping is the most expensive thing you can do with a generator. Every annual service report we deliver has at least one item that would have caused trouble in another 6 months — that's the value math you're getting.