Updated
Service frequency
How Often Should a Generator Be Serviced?
A generator typically needs a service every 100 to 500 running hours or every 6 to 24 months, whichever comes first: about 100 hours or 6 months for Honda portables, 200 hours or 2 years for Generac home standby sets, and 500 hours for a Perkins diesel minor service. The manual for your engine sets its exact interval.
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- Hours or months, whichever comes first
- Standby sets run on the calendar
- Prime sets run on the hour meter
- Onsite across Gauteng
Hours and calendar
How to work out when your generator is due
Your generator runs on two clocks. The hour meter counts the work the engine does. The calendar counts the time that oil, fuel, coolant and the battery spend ageing. Published schedules give both limits and apply whichever comes first. Generac, for example, lists 200 hours or 2 years for its home standby sets, and cuts that to 100 hours in very hot or cold conditions.
A standby set that only runs during power outages usually reaches the calendar limit first. A prime set that runs as your main supply reaches the hour limit first, sometimes within weeks. At 8 hours a day, a 500-hour interval arrives in about two months.
If you do not know when your set was last serviced, we record the hour reading and carry out a full service, so you start from a clean baseline. To see what each level of service includes, read our service intervals guide.
What changes the interval
Standby, prime and the conditions that bring a service forward
Standby duty: the calendar usually decides
A set that runs a few hours a year rarely reaches its hour limit. Its oil, coolant, fuel and battery still age, so you book the service on the calendar limit, such as the 2 years Generac gives for home standby sets.
Prime duty: the hour meter decides
A set that carries your site every day builds hours fast. FEMA course material puts the oil and filter change at every 240 operating hours for diesel sets in continuous emergency use, which is about every 10 days of round-the-clock running.
Heat, cold and dust
Generac halves its home standby oil interval to 100 hours in very hot or cold conditions. Dust clogs air filters faster, so we check the air filter at every visit on dusty sites and change it when it needs it.
Light loads and short runs
Long runs at light load and frequent short starts are hard on a diesel. If your set mostly idles, or runs for a few minutes at a time, we may advise servicing before the hour limit and a run on proper load.
The first service on a new engine
Many new engines need an early first oil change. Honda’s portable schedule, as reported by SlashGear, calls for the first change after 20 hours or 1 month, then every 100 hours or 6 months.
Faults do not wait for the interval
Leaks, smoke, hard starting or a weak battery justify a visit now, whatever the meter says. Booking the repair early usually costs less than a no-start during the next outage.
Typical published intervals
These are published schedules for particular engines and generators. They show the range you can expect. Your own engine’s manual gives the exact figure for your set.
| Engine or generator type | Typical interval | Source |
|---|---|---|
| Honda portable petrol generators | First oil change at 20 hours or 1 month, then every 100 hours or 6 months | SlashGear, reporting Honda’s schedule |
| Generac home standby generators | Oil and filter every 200 hours or 2 years, whichever comes first; every 100 hours in very hot or cold conditions | Generac support: home standby maintenance schedule |
| Diesel generators in continuous emergency use | Oil and filter every 240 operating hours | FEMA IS-815: generator servicing requirements |
| Perkins diesel engines | Minor service every 500 hours; major services at 1,000, 2,000, 3,000 and 4,000 hours | Perkins: How do you maintain a Perkins engine? |
Enter your own figures in our service due checker to see whether your next service is due. Our service intervals guide lists what each level of service includes.
Worked example: which limit comes first?
Take the Generac home standby schedule of 200 hours or 2 years. How many hours your set runs in a year decides which limit you reach first.
| Running hours per year | Hour limit reached after | Service is due after |
|---|---|---|
| 50 hours (occasional outages) | 4 years | 2 years, on the calendar limit |
| 100 hours | 2 years | 2 years, both limits together |
| 400 hours (frequent outages) | 6 months | 6 months, on the hour limit |
| 1,000 hours | About 10 weeks | About 10 weeks, on the hour limit |
Arithmetic: 200 hours divided by your hours per year. Source for the interval: Generac support: home standby maintenance schedule. Swap in the figures from your own manual.
Related Pages
Intervals, hours and the service itself
Common Questions
Questions about generator service frequency
How often should a generator be serviced?
Typically every 100 to 500 running hours or every 6 to 24 months, whichever comes first. Generac lists 200 hours or 2 years for its home standby sets, and Perkins lists a minor service every 500 hours for its diesel engines. The manual for your engine gives its exact interval.
How often should a standby generator be serviced?
Usually on the calendar limit, because standby sets rarely reach their hour limit. On a Generac home standby set that means at least every 2 years, or sooner if it reaches 200 hours. A yearly check of the battery, fuel and coolant catches problems in between.
How often should a prime or continuously running generator be serviced?
By the hour meter. FEMA course material for diesel sets in continuous emergency use gives an oil and filter change every 240 operating hours. That is about every 10 days if the set runs around the clock.
Do frequent power outages change how often I need a service?
Yes, because they add running hours quickly. At 4 hours a day, a 200-hour interval arrives in about 7 weeks. Watch the hour meter rather than waiting for a yearly visit.
Do heat or dust shorten the interval?
Yes. Generac cuts its home standby oil interval from 200 to 100 hours in very hot or cold conditions, and dust clogs air filters faster. We check the air filter at every visit on dusty sites.
When should a new generator have its first service?
Often earlier than the routine interval. Honda’s portable schedule, as reported by SlashGear, puts the first oil change at 20 hours or 1 month. Check the first-service line in your manual.
How do I know when my generator was last serviced?
Look for a service sticker, an invoice or a logbook entry with the hour reading. If you find none, we record the hours and the date at the next service so you have a baseline.
What does each service include?
Each level adds work: daily owner checks, weekly fuel-water draining, the oil-and-filter service and deeper major services on larger diesels. Our service intervals guide lists what each level includes.
Still unsure what the fault is? Call or WhatsApp 082 057 4605 for onsite diagnosis.
Service Areas
Onsite visits across Gauteng
We come to your generator anywhere in Gauteng, 24/7. Choose your region for local suburbs, call-out details and the faults we see most there.
What to send before we attend
These details help us plan the visit and bring the right parts. Send what you can on WhatsApp; if you can’t find the model number, we still book the visit.
- Location
- The suburb or site, so the visit can be booked in the right area.
- Make and model
- The generator brand and model, if they are known.
- kVA
- The size printed on the data plate.
- Fuel type
- Diesel, petrol, LPG, natural gas, or dual-fuel.
- Controller model
- The module name on the panel, when it is visible.
- Fault or alarm
- What the set does, and any text on the screen.
- Photos
- The generator, the data plate, and the controller or alarm. Send these on WhatsApp.
Book a Visit
Send your hours and last service date
We use them to work out which service is due. If you have neither, we record both at the visit.
- Call
- 082 057 4605
- Message us on WhatsApp
What happens next
- We reply with questions about the generator, or to book a visit.
- A technician comes to you. For a breakdown we arrive within 1 hour.
- The fault is diagnosed on site and you get a written quote. No work starts until you accept it.
Charlie, lead technician: Degree in Mechanical Engineering, Degree in Electrical Engineering, Diesel Plant Fitter. Generator specialists since 2000.