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Gas generator maintenance is the routine that keeps a standby generator ready to start when the power goes out. Filters, oil and spark plugs wear with use, and a generator that sat idle through the year needs the same checks as one that ran through an outage. This guide walks through the service steps, the intervals the makers list, and how to match a maintenance kit to the engine.
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The quick answer: gas generator maintenance
Service a gas generator on the interval the maker lists, and match the kit to the engine size and build year. The Generac kits in this guide list service every 200 hours or 2 years, with an air filter, an oil filter, spark plugs, a funnel and a reminder sticker in the box, and oil bought separately. Check the model and serial number plate on the enclosure before ordering a kit, since a kit that fits a 999cc engine will not fit a 530cc engine.
Step 1: Check the service interval
Start with the manual and the reminder sticker on the enclosure. The Generac 6485 kit (on Amazon) lists service every 200 hours or 2 years, and the RARAYC 6485 kit (on Amazon) lists the same interval, with more frequent service in dusty environments. The Generac 5656 kit (on Amazon) for liquid-cooled standby generators lists the same 200-hour or 2-year interval. When the hours or the years run out, service the generator even if it ran fine at the last outage.
Step 2: Match the kit to the engine
Check the engine size and build year before ordering. The Generac 6485 kit fits 20kW, 22kW, 24kW and 26kW standby generators with a 999cc V-Twin engine built in 2013 or later, and the RARAYC 6485 kit fits 16kW to 26kW models with the same 999cc engine from 2013 or later. The Generac 5664 kit fits (on Amazon) 13kW to 17kW generators built between 2008 and 2012, while the Generac 5663 kit fits 11kW models with a 530cc engine from the same years. The Generac 5656 kit fits 2.4-liter liquid-cooled generators at 25 kilowatts and 45 kilowatts. A kit that fits a 999cc engine will not fit a 530cc engine, so read the model and serial number plate on the enclosure first.
The Generac 5663 (on Amazon) listing gives 11kW in its title and 10kW in its bullets, and calls the engine air-cooled in one place and liquid-cooled in another, so check the plate on the enclosure before ordering that kit.
Step 3: Change the filters and spark plugs
Work through the kit contents in the order the instruction manual shows. The Generac 6485 kit holds an air filter, a foam air pre-cleaner, a spin-on oil filter, 2 pre-gapped spark plugs, an angled funnel, a microfiber cloth, a reminder sticker and an instruction manual. The RARAYC 6485 kit holds the same filters with a paper funnel and an oil wipe. The Generac 5656 kit holds an air filter, an oil filter, 4 spark plugs, a funnel, a chamois and a reminder sticker. Wear work gloves during installation, as the RARAYC listing advises, and use standard hand tools: the Generac 6485 listing states no special tools are required.
Step 4: Change the oil and finish up
Oil is not included in these kits, so buy it separately to the spec the manual lists. The Generac 6485 listing calls for SAE 5W-30 full synthetic engine oil, while the Generac 5W-20 kit for 20kW to 26kW generators lists 2 quarts in its size. The angled funnel in the kit prevents spills during oil changes, and the microfiber cloth or chamois handles cleanup. Put the reminder sticker on the enclosure with the next service date, and run the generator briefly to check for leaks before putting it back on standby.
| Maintenance kit | Fits | Service interval | In the box |
|---|---|---|---|
| Generac 6485 | 20kW to 26kW, 999cc, 2013 or later | 200 hours or 2 years | Air filter, pre-cleaner, oil filter, 2 spark plugs |
| RARAYC 6485 | 16kW to 26kW, 999cc, 2013 or later | 200 hours or 2 years | Air filter, oil filter, paper funnel, oil wipe |
| Generac 5664 | 13kW to 17kW, 2008 to 2012 | Not stated | Air filter, oil filter, spark plug, funnel |
| Generac 5663 | 11kW, 530cc, 2008 to 2012 | Not stated | Air filter, oil filter, spark plug, funnel |
| Generac 5656 | 2.4-liter liquid-cooled, 25kW and 45kW | 200 hours or 2 years | Air filter, oil filter, 4 spark plugs |
Ways to keep a generator ready
- Service on the interval the maker lists, every 200 hours or 2 years.
- Match the kit to the engine size and build year, and check the plate on the enclosure first.
- Keep a spare air filter and oil filter on hand, so a service does not wait on parts.
- Keep the generator in a ventilated spot with the enclosure vents clear.
- Put the reminder sticker on the enclosure after each service, so the next date is in plain sight.
FAQ: power away from the grid
How often should I service a gas generator?
Follow the interval the maker lists. The Generac 6485, RARAYC 6485 and Generac 5656 kits all list service every 200 hours or 2 years, with more frequent service in dusty environments. Put the reminder sticker on the enclosure after each service so the next date is in plain sight.
What is in a generator maintenance kit?
A kit holds the consumables for a service: an air filter, an oil filter, spark plugs, a funnel and a reminder sticker, with an instruction manual. The Generac 6485 kit holds an air filter, a foam pre-cleaner, a spin-on oil filter, 2 spark plugs, an angled funnel, a microfiber cloth, a sticker and a manual. Oil is not included, so buy it separately to the spec the manual lists.
How do I know which maintenance kit fits my generator?
Check the engine size and build year on the model and serial number plate. The Generac 6485 kit fits 999cc engines built in 2013 or later, the Generac 5664 kit fits 13kW to 17kW generators built between 2008 and 2012, and the Generac 5656 kit fits 2.4-liter liquid-cooled generators. A kit that fits a 999cc engine will not fit a 530cc engine.
Does a maintenance kit include oil?
No. Oil is not included in the kits in this guide, so buy it separately to the spec the manual lists. The Generac 6485 listing calls for SAE 5W-30 full synthetic engine oil, and the Generac 5W-20 kit lists 2 quarts in its size. See the best engine oil for portable generator for options.
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