Generator Maintenance Checklist: Annual and Winter Guide

A generator only protects your home if it starts when the power goes out. In Canada, that usually means the middle of an ice storm, at -20°C, in the dark. Regular maintenance is what makes the difference between a generator that runs and one that fails at the worst moment.

This guide gives you a complete annual and winter generator maintenance checklist for standby and portable generators. It covers what to inspect, how often to service, what maintenance costs, and when to call a professional technician.

Why Is Regular Generator Maintenance Important?

Regular generator maintenance keeps your generator reliable, safe and efficient, and protects your warranty. A generator can sit idle for months, so small problems like a weak battery or old oil often go unnoticed until an outage.

• Reliable starts: dead batteries, stale fuel and dirty filters are the most common reasons generators fail to start.

• Longer engine life: clean oil and filters reduce wear and help a standby generator last 15 to 25 years.

• Safety: inspections catch fuel leaks, exhaust leaks and loose wiring that can cause fires or carbon monoxide (CO) exposure.

• Warranty protection: manufacturers such as Cummins and Generac require documented maintenance to keep warranty coverage valid.

• Lower repair costs: a $300 service visit costs far less than an emergency engine repair during an outage.

Annual Generator Maintenance Checklist

An annual generator service covers the engine, fluids, filters, battery, fuel system, cooling, connections, exhaust and a load test. Always follow your owner's manual first, since service intervals vary by model and running hours.

• Inspect the engine and check for leaks

• Change the oil and oil filter

• Inspect or replace the air filter

• Test the battery and clean the terminals

• Inspect spark plugs and fuel filters

• Check coolant and the cooling system

• Inspect belts, hoses and connections

• Test the generator under load

• Inspect the exhaust and ventilation

Inspect the Engine and Check for Leaks

Inspect the engine and enclosure for oil, fuel and coolant leaks at every service. Look for wet spots, stains on the pad, and residue around gaskets, fittings and the fuel line.

Also check for rodent nests, insect activity, debris and loose panels inside the enclosure. A gas smell near the generator means you should shut off the fuel supply and call a licensed gas technician.

Change Engine Oil and Replace the Oil Filter

Change the engine oil and oil filter every 100 to 200 running hours or at least once a year, whichever comes first. New generators often need a first oil change after a short break-in period.

Use the oil grade and type listed in your manual. Many manufacturers recommend synthetic 5W-30 for standby units in cold climates because it flows better at low temperatures. Check the oil level before every season.

Inspect and Replace Air Filters

Inspect the air filter at each service and replace it at least once a year, or sooner in dusty or rural areas. A clogged air filter reduces airflow, wastes fuel and lowers output.

Check the air intake for leaves, pollen and nests. Never run the generator without an air filter.

Check the Battery and Electrical Connections

Test the starting battery every year and replace it every 3 to 5 years. The battery is the number one cause of standby generator start failures.

Clean corrosion from the terminals, tighten the cables and check the battery charger. Inspect wiring, the controller and the automatic transfer switch (ATS) for loose connections, burn marks or damaged insulation.

Inspect Spark Plugs and Fuel Filters

Inspect spark plugs every year and replace them every 1 to 2 years or as your manual specifies. Worn plugs cause hard starting, misfires and higher fuel use.

Check the plug gap and look for carbon deposits. On diesel and some gasoline units, replace the fuel filter on schedule and drain any water from the fuel water separator.

Check Coolant Levels and Cooling Systems

On liquid-cooled generators, check the coolant level and concentration every year and flush the coolant every 2 to 3 years. Most air-cooled home standby units, such as the Generac Guardian Series, have no coolant but need clean cooling fins and airflow.

Inspect the radiator for debris and the fan for damage. Test the coolant's freeze protection before winter.

Inspect Belts, Hoses, and Connections

Inspect belts and hoses every year for cracks, fraying, swelling and looseness. Replace worn parts before they fail during an outage.

Check fuel line fittings, flexible gas connectors, hose clamps and electrical connectors. Vibration can loosen connections over time.

Test the Generator Under Load

Test the generator under load at least once a year to confirm it can carry your home's electrical demand. A weekly self-test usually runs without load, so it does not prove full performance.

A technician simulates a power outage to confirm the automatic transfer switch transfers the load and returns it when utility power comes back. Larger and commercial units may need a load bank test.

Inspect the Exhaust and Ventilation System

Inspect the exhaust system, muffler and ventilation every year for leaks, rust, blockages and damage. Exhaust leaks can release carbon monoxide.

Keep the area around the generator clear of plants, storage and debris. Confirm the unit still meets the manufacturer's clearances from windows, doors and vents, and install CO alarms inside your home.

Winter Generator Maintenance Checklist

Winter generator maintenance prepares your generator to start and run in freezing temperatures, snow and ice. Complete it in the fall, before the first storm, and check again after heavy snowfall.

• Test cold-weather starting

• Test and charge the battery

• Switch to winter-grade oil

• Check fuel quality and add anti-gel or stabilizer

• Test coolant freeze protection

• Clear snow and ice from intakes and exhausts

• Protect against moisture and corrosion

Check Cold-Weather Starting Performance

Run the generator in cold conditions before winter to confirm it starts quickly and runs smoothly. Hard starting in the cold usually points to a weak battery, thick oil or a fuel problem.

Check the operating temperature rating for your model. Standard Cummins QuietConnect units run down to -18°C, while extreme cold weather models run to -40°C. In colder regions, a battery warmer, oil heater or block heater improves starting.

Inspect Battery Condition and Charge

Test the battery voltage and charge before winter, because cold weather reduces battery capacity. A battery that starts the engine easily in summer may fail at -20°C.

Confirm the built-in battery charger works, clean the terminals and replace any battery older than 3 to 5 years. Keep a trickle charger on portable generators during storage.

Use the Recommended Winter-Grade Engine Oil

Use the winter-grade oil your manufacturer recommends, often synthetic 5W-30, so the engine turns over easily in the cold. Thick summer oil slows cranking and increases engine wear at start-up.

Check your manual's temperature chart for the correct viscosity, and top up the oil before winter begins.

Check Fuel Quality and Prevent Fuel Gelling

Check fuel quality before winter. Diesel can gel in extreme cold, and gasoline goes stale after a few months.

• Diesel: use winter-blend diesel or add an anti-gel additive, and drain water from the fuel separator.

• Gasoline: add fuel stabilizer, or use fresh fuel each season.

• Natural gas and propane: no gelling, but check the propane tank level and have your supplier confirm the regulator and lines are clear of ice.

Inspect Coolant and Freeze Protection

Test the coolant's freeze point on liquid-cooled generators before winter. Coolant that is too diluted can freeze, crack the engine block and damage the radiator.

Use the coolant type and mix ratio in your manual, and top up to the correct level. A technician can test the concentration with a refractometer or hydrometer.

Keep Snow and Ice Away From Air Intakes and Exhausts

Keep snow, ice and drifts clear of the generator's air intakes, exhaust outlets and enclosure vents. A blocked exhaust can cause overheating and push carbon monoxide toward your home.

Clear at least a metre around the unit after each snowfall. Avoid placing the generator under roof eaves, where snow and ice fall, and never cover it with a tarp while it runs.

Protect the Generator From Moisture and Corrosion

Protect the generator from moisture, condensation and road salt to prevent rust and electrical faults. Freeze-thaw cycles in Canadian winters let water reach connectors and the control panel.

Check enclosure seals and door gaskets, clean corrosion from terminals, and apply dielectric grease to connections if recommended. Keep the pad level and well-drained so water does not pool under the unit.

How Often Should You Service a Generator?

Service a standby generator at least once a year, and twice a year if you use it often or live in a harsh climate. Portable generators need service based on running hours and before each season.

After a long outage, schedule an extra oil change, since the generator may have run for dozens of hours in a few days.

Standby vs Portable Generator Maintenance Requirements

Standby generators need professional annual service and automatic self-tests, while portable generators need more hands-on owner maintenance, especially fuel care.

The biggest portable generator risk is stale gasoline, which gums up the carburetor. Read our Dual Fuel Inverter Generator guide for portable options.

Common Generator Maintenance Mistakes to Avoid

Most generator failures come from a few avoidable mistakes. Avoid these to keep your generator ready.

• Skipping the annual service because the generator "ran fine" during the weekly test.

• Ignoring the battery until it fails to start the engine in the cold.

• Leaving gasoline in a portable generator for months without stabilizer.

• Using the wrong oil grade for winter temperatures.

• Never testing under load, so overloads and transfer switch faults go unnoticed.

• Letting snow bury the unit or block the intake and exhaust.

• Turning off the weekly self-test to avoid noise.

• Running a portable generator indoors or in a garage, even with the door open, which risks carbon monoxide poisoning.

• Not keeping a service log, which can void the warranty.

• Attempting gas or electrical repairs yourself instead of calling a licensed technician.

When Should You Call a Professional Generator Technician?

Call a professional generator technician for annual standby service and any time the generator shows warning signs. Gas, electrical and transfer switch work should always be done by licensed professionals.

Call a technician if your generator:

• Fails to start or starts and shuts down

• Shows a warning, fault code or alert in the Generac Mobile Link or Cummins Cloud Connect app

• Misses its weekly self-test

• Makes knocking, grinding or unusual noises

• Produces black smoke or leaks oil, fuel or coolant

• Smells of gas

• Fails to transfer power during an outage or does not switch back

• Shows fluctuating voltage or flickering lights

• Has not been serviced in more than 12 months

Volts Energies technicians provide generator repair and maintenance services across Canada for Cummins, Generac, Winco and Elios generators, including automatic transfer switch testing and load bank testing.

How Much Does Generator Maintenance Cost?

Annual standby generator maintenance typically costs $250 to $450 in Canada for a residential unit. Portable generator maintenance costs much less when owners do the basic work themselves.

Costs rise with generator size, liquid-cooled engines, emergency call-outs, travel to rural areas and replacement parts. A maintenance plan often includes priority scheduling during storms. See what a standby generator costs to install for the full cost of ownership.

Prices are typical 2026 estimates before tax and vary by region and model.

How to Prepare Your Generator for Extended Storage

Preparing a generator for storage prevents stale fuel, corrosion and battery failure. It mainly applies to portable generators stored for more than 30 days.

1. Treat or drain the fuel. Add fuel stabilizer and run the engine for 5 to 10 minutes, or drain the tank and run the carburetor dry.

2. Change the oil so acidic used oil does not sit in the engine.

3. Clean the generator, removing dirt, grass and debris from the vents and cooling fins.

4. Remove or maintain the battery with a trickle charger.

5. Protect the cylinder by following your manual's fogging or spark plug procedure if recommended.

6. Store it dry and ventilated, off the ground, away from fuel-burning appliances, with a breathable cover.

7. Shut off the fuel valve on dual-fuel and propane units, and store propane cylinders outdoors.

For standby generators, keep the unit in automatic mode. Leave the weekly self-test running and service it on schedule, even if outages are rare.

Final Thoughts

A well-maintained generator is one that starts when you need it most. Follow an annual maintenance checklist covering oil, filters, the battery, spark plugs, cooling, connections, exhaust and a load test. Before winter, add cold-weather checks for the battery, oil grade, fuel quality, coolant and snow clearance. Standby generators need professional service at least once a year, while portable units need regular owner care and proper storage. Keep a service log to protect your warranty, and call a licensed technician whenever warning signs appear.

FAQs

How often should a standby generator be serviced?

A standby generator should be professionally serviced at least once a year. Service it twice a year if it runs often, after long outages, or in harsh climates.

How often should I change the oil in my generator?

Change the oil every 100 to 200 running hours or once a year for most standby generators. Portable generators often need an oil change every 50 to 100 hours. Always follow your owner's manual.

What oil is best for a generator in winter?

Many manufacturers recommend synthetic 5W-30 for cold weather because it flows quickly at low temperatures. Check your manual's temperature chart for the exact grade.

How long does a generator battery last?

A generator starting battery usually lasts 3 to 5 years. Test it every year and before winter, since cold weather reduces battery capacity.

Why won't my generator start in cold weather?

The most common causes are a weak battery, oil that is too thick, stale or gelled fuel, or a blocked air intake. A battery warmer or oil heater helps in very cold regions.

Should my standby generator run a weekly self-test?

Yes. The weekly self-test, or exercise cycle, keeps the engine lubricated, charges the battery and confirms the generator is ready. Do not disable it.

Can I maintain my generator myself?

You can handle basic tasks such as visual checks, clearing snow and debris, and oil changes on portable units. Standby generator service, gas connections and transfer switch work should be done by a licensed technician.

Does skipping maintenance void my generator warranty?

It can. Manufacturers such as Cummins and Generac may deny warranty claims if required maintenance was not completed. Keep a dated service log and receipts.

How much does annual generator maintenance cost in Canada?

Annual residential standby generator maintenance usually costs $250 to $450. Maintenance plans with priority storm service often cost $300 to $500 per year.

Do natural gas and propane generators need fuel maintenance?

They do not need fuel stabilizer or anti-gel additives. However, you should check gas lines, regulators and propane tank levels, and keep regulators clear of ice and snow.