Generator maintenance comes down to fresh oil, clean air, good fuel and regular test runs. Change the oil after the short break-in period, then on the hours-or-months schedule in your owner's manual. Check oil before each use, keep the air filter clean, stabilize or drain gasoline in storage, and start the generator regularly so it's ready for an outage.
Key facts
- Honda's EU2200i manual schedules the first oil change at the first month or 20 hours of use, and asks you to check the oil level every time you use it.
- Generac's home standby generators need a break-in oil change after the first 25 hours, then every 200 hours or 2 years, whichever comes first.
- Generac shortens that to every 100 hours when the unit runs below 40°F or above 85°F.
- Honda recommends draining the carburetor if a gasoline generator runs less than once a month.
- Generac standby units run a short automatic exercise on a weekly, biweekly or monthly schedule.
Why does a generator need maintenance if it rarely runs?
A backup generator might sit for months, then run for days straight in a storm. Both are hard on an engine. Sitting lets gasoline go stale and gum up the carburetor, batteries run down, and oil age. Long runs burn through oil hours fast. Stale fuel, low oil and a dead battery are all problems that routine care can catch before you need the power. (If engine upkeep isn't for you, compare a power station vs a generator for small loads.)
Your owner's manual is the authority for your model. The intervals below come from manufacturer manuals and service pages, and they differ between models.
When should I do the break-in oil change?
New engines shed tiny metal particles as parts wear in, so the first oil change comes early.
- Honda EU2200i (portable inverter): the manual's schedule puts the first oil change at the first month or 20 hours of use.
- Generac home standby: change the oil and filter after the first 25 hours of run time (20 hours on the 7.5 kW PowerPact).
A new portable may also ship without oil. Fill it to the level and grade the manual specifies before the first start.
How often should I change generator oil?
After break-in, follow the maker's interval, which is given in both hours and calendar time. Change at whichever comes first: oil ages even when the generator sits.
| Generator (source) | Break-in change | Regular interval |
|---|---|---|
| Honda EU2200i portable (owner's manual) | First month or 20 hours | On the months-or-hours schedule in the manual; check level every use |
| Generac home standby (Generac support) | 25 hours (20 on 7.5 kW PowerPact) | Every 200 hours or 2 years; every 100 hours in temperatures below 40°F or above 85°F |
| Briggs & Stratton guidance | See owner's manual | 50-hour intervals for portable generators; annually or every 100 hours for air-cooled standby units |
During a long outage, those hours add up quickly. A generator running around the clock reaches 50 hours in about two days and 100 hours in about four. Keep the right oil and a funnel with your fuel, and check the level every time you refuel (with the engine off and cool). Many generators have a low-oil shutoff, but it's a safeguard, not a maintenance plan.
Use the oil grade your manual specifies. Generac, for example, recommends 5W-20 full synthetic for its home standby generators. Portables often list different grades for different temperatures.
Should I run my generator every month?
Running it regularly is the simplest way to find out it still works. A short monthly run under a light load circulates oil, keeps seals and the carburetor wet with fresh fuel, charges the starting battery on electric-start models, and shows you any problems while there's time to fix them. Honda's fuel advice treats any generator that runs less than once a month as one that needs its carburetor drained, which gives you a natural choice: run it monthly or prepare it for storage.
A monthly run is also a good time to test the full setup: cords, the inlet and transfer switch if you have one, and how long it takes you to get everything going in the dark. Follow every generator safety rule for test runs too: outdoors only, at least 20 feet from the house with the exhaust pointed away.
Standby generators exercise themselves
Home standby generators run an automatic exercise when left in auto mode. Generac lets owners set it to weekly, biweekly or monthly. Run times vary by model; Generac lists 5 minutes for its Guardian series and 12 minutes weekly for the 7.5 kW PowerPact. Check after power returns from an outage that the unit is back in auto mode.
How do I keep gasoline from going bad?
Honda warns that stale fuel can cause starting and running problems. Its fuel guidance for its generators:
- Add fuel stabilizer to your gas can every time you fill it, following the stabilizer maker's directions.
- Avoid fuel with more than 10% ethanol.
- Use a self-sealing can to limit vapor loss and moisture.
- Store the generator in a cool, dry place out of direct sunlight.
- Stabilizer doesn't revive old fuel, and even treated fuel can deteriorate in long storage.
If you want fuel that keeps for years, propane is the alternative. See dual fuel generators for the trade-offs.
How do I store a generator?
Honda's EU2200i manual sets out storage steps by how long the generator will sit:
| Storage time | What Honda's manual says to do |
|---|---|
| Less than 1 month | No special preparation |
| 1 to 2 months | Fill with fresh gasoline and add stabilizer |
| 2 months to 1 year | Fresh, stabilized gasoline and drain the carburetor float bowl |
| 1 year or more | Drain the fuel tank and carburetor, change the oil, and lubricate the cylinder as the manual describes |
Store the generator level, with the engine switch and fuel vent off, in a well-ventilated area away from flames and sparks, under a breathable cover rather than plastic. Store fuel cans outside the living space in approved containers, as OSHA advises.
How often should I change the air filter and spark plug?
Air filter
A dirty air filter chokes the engine and wastes fuel. Honda's manual calls for checking the air cleaner before each use and cleaning it on schedule, more often in dusty conditions. Briggs & Stratton suggests inspecting a paper filter every six months by holding it up to the light and replacing it if it's dark or blocked, with a new filter as part of annual service.
Spark plug
A worn or fouled plug causes hard starting. Honda's schedule includes periodic spark plug inspection and replacement, and Briggs & Stratton includes a new plug in annual service. Use the plug type and gap your manual lists.
Spark arrester
Many portables have a spark arrester screen in the muffler. Honda's EU2200i manual calls for cleaning it every 100 hours.
What does standby generator service include?
Home standby generators have their own schedule, often tracked by the controller with a maintenance light. Generac's yearly checklist covers:
- Checking for water intrusion
- Inspecting the battery
- Testing the fuel system for leaks
- Looking for corrosion and applying protection
- Changing the oil and filter based on hours, time and environment
Generac says owners can do routine tasks by following the manual or hire a certified dealer, and that either way you should keep maintenance records. Electrical and gas connections, including the transfer switch, are work for licensed professionals.
Generator maintenance checklist
- Every use: check oil level and air filter; look for fuel leaks and damaged cords.
- Monthly: start and run under a light load, or prepare it for storage; test CO alarms.
- Break-in: first oil change at the interval in your manual (for example, 20 hours on Honda's EU2200i, 25 on Generac standby units).
- Regularly: oil changes, air filter, spark plug and spark arrester per the manual's hours-or-months schedule.
- Before storm season: fresh stabilized fuel, spare oil, filter and plug, and a check that your load plan still fits. Our generator size calculator and what to run during an outage guide help.
Questions people ask
How often should I change the oil in a portable generator?
Follow your manual. Honda's EU2200i calls for the first change at one month or 20 hours, then regular changes on its hours-or-months schedule, and Briggs & Stratton cites 50-hour intervals for portables.
How often should a standby generator be serviced?
Generac calls for an oil and filter change every 200 hours or 2 years, every 100 hours in extreme temperatures, and a yearly inspection of the battery, fuel system and enclosure.
Can I leave gas in my generator?
For short periods, with stabilizer. Honda recommends fresh, stabilized fuel for storage up to two months and draining the carburetor beyond that or if the generator runs less than once a month.
How long should I run my generator each month?
Your manual is the best guide. A short run under a light load is enough to confirm it starts and makes power; standby units do this automatically, with Generac's exercises lasting about 5 to 12 minutes depending on model.
Do I need to change the oil during a long outage?
Possibly. A generator running nonstop reaches 50 to 100 hours in two to four days, which can reach the maker's interval. Check the level at every refueling and change it when the manual says.
Sources
- Honda: EU2200i generator owner's manual
- Honda: Generator fuel recommendations
- Generac: How do I perform the yearly maintenance for my home standby generator?
- Generac: What is Schedule A maintenance for my home standby generator?
- Generac: What is a generator exercise?
- Briggs & Stratton: Expert guide to generator maintenance
- OSHA: Using portable generators safely (fact sheet)
