Does Standby Generator Fuel Go Bad?

Standby generators provide emergency power to homes and businesses when required. But what happens if (and when) the standby generator fuel goes bad?

How long can you leave fuel in a generator?

A generator’s fuel tank may hold untreated gasoline for anywhere from one to six months, depending on a variety of circumstances. Generator gas tanks are not as airtight as gas tanks, therefore the gasoline oxidizes and degrades more quickly.

Does generator fuel go bad?

The answer is that it depends on the type of fuel being used. If you are using standby generators that run on petrol or diesel, then the fuel will go bad over time and will need to be replaced. However, if you are using a standby generator that runs on natural gas or propane, it will last longer.

How do I keep gas from going bad in my generator?

Fill the tank of your generator with a fuel stabilizer. This prevents gumming up while it’s in storage. Keep the fuel cutoff valve on your generator closed so that old gas does not clog the carburetor by running your generator motor dry.

Can I use 1-year-old gas in my generator?

Maybe. However, if the color of the gasoline seems to have changed, it indicates that the gasoline has oxidized and is producing gums, varnishes, and deposits. Using such fuel in your generator can leave toxic deposits in the combustion zones of the generator motor, which might damage the generator itself.

Should you use premium gas in a generator?

You should use unleaded gasoline that has not been contaminated. Fuel must be 87 octane/87 AKI or above. Non-ethanol-premium gasoline is preferred, however up to 10% ethanol is permissible.

Is it better to store a generator with or without gas?

When storing your generator for an extended period of time, it’s best to remove the fuel tank completely. If you don’t want to waste gasoline by running the generator to empty, you may transfer the gas to your car. Unleaded gasoline (normal, unleaded) is the fuel of choice for most generators.

Standby generators might fail if the fuel, such as gas or diesel, becomes contaminated. Fuel should be stored outside rather than within a generator for this reason. Your generators should be stored in a dry place until they are needed.

Just remember that if safeguards aren’t followed, diesel and gasoline might cause serious harm. When using a gas-powered generator, it’s best to avoid storing fuel within the machine if possible.

How long is gas good for?

Gas is usually good for six months to a year.

Related Questions and Answers

Should I put a fuel stabilizer in my generator?

Your generator may last longer if you use a fuel stabilizer to keep the carburetor clean. We usually suggest draining your carburetor manually when storing a generator for an extended period of time.

How much Stabil do I need for 5 gallons of gas?

It is recommended that you add one ounce (30 mL) of STA-BIL 360° Protection to gasoline, gas/oil mixes, or ethanol blends in order to protect against ethanol degradation.

What is the most efficient fuel for a generator?

Diesel is considered the most efficient fuel for generators.

Can you add a fuel stabilizer to old gas?

One to three years is the average lifespan of stabilized gasoline. With fresh gasoline, stabilizers are most effective; they are useless in slowing the deterioration of old gas, and they cannot restore contaminated fuel to working condition.

How long does oil last in a generator?

After just 25 hours of use, the oil in the majority of new generators has to be changed. Then you’ll have to empty and refill every 50 to 60 hours.

How often should I start my generator?

A few minutes of running your generator every 30 days is always a good idea, even if you’ve followed these storage instructions to the letter. The oil will be circulated throughout the engine, which will assist to keep its components oiled.

What fuel does generac use?

In the same way, as a central air conditioning unit stands outdoors, this device is powered by natural gas or liquid propane (LP).

Is Predator a good generator brand?

Predator generators are excellent choices for your home, workplace, or recreational vehicle. They are well-known for their affordable, strong engines that give dependable and steady power supply in any circumstance.

What kind of fuel do Honda generators use?

Honda generators use non-leaded petrol.

What does a ‘standby generator’ mean?

This video should help:

Is seafoam or Stabil better?

Sea Foam or Stabil: Which is better? For up to 24 months, both Sea Foam and Stabil Storage can store gasoline in excellent condition. Stabil Storage, on the other hand, costs half as much as Seafoam but is 2.5 times as powerful.

What is the difference between Stabil and Stabil 360?

If you’re going to be storing your generator or gear for more than one season or not utilizing gas for a long length of time, red Storage Stabil is also a good idea.

How do I keep my generator carburetor from gumming up?

Use a gas stabilizer like Stabil or something like it. It’s recommended to empty the gas and run the carburetor dry, or to exercise the carburetor every few months, to keep it in peak condition for extended lengths of time.

Is it safe to store a generator in a garage?

Even if the garage door is open, do not run a generator in the garage. When installing generators, be sure that exhaust gases can’t enter the residence via windows and doors or other openings. Your home’s appliances all draw a certain amount of power.

Where do you store a generator when not in use?

Whenever a generator is not in operation, it must be properly kept and maintained. The gasoline in your generator’s fuel tank has a shelf life of up to one year when properly stabilized with a fuel stabilizer and stored in a cool, dry location.

Is 2-year-old gasoline still good?

Degradation begins right away, although most gas may be safely stored for a month or two before deterioration sets in. But gas longer than two months old is typically safe to use, with just small performance losses. Fuel that is more than a year old may create problems, such as engine sputtering and blocked injectors, as well as engine noises.

Does fuel go out of date?

Only a few months after putting gasoline in a container does the quality begin to deteriorate – and much less time if the fuel is polluted. At 20 degrees Fahrenheit, fuel has a six-month shelf-life; at 30 degrees, it has a three-month shelf-life.

How does STA-BIL 360 work?

STA-BIL 360 Protection uses a PEA fuel system cleaning, industry-leading corrosion inhibitors, and water removers to provide all-around security for your vehicle. For up to 12 months, it maintains the gasoline fresh by cleaning the carburetors, fuel injectors, and intake valves of the engine.

How long is STA-BIL good for?

All STA-BIL brand items have a two-year shelf life once they’ve been opened, as long as they’ve been well-sealed and kept cold and dry. Using an outdated bottle of STA-BIL will not do any damage, although it may not be as effective.

How many ounces of seafoam is in a gallon of gas?

A single gram of seafoam will be in a gallon of gas.

What is the cheapest fuel to run a generator?

Natural gas and diesel are the two most affordable fuels, yet comparing the two is difficult. However, although diesel costs more than natural gas, it has a greater energy density and so burns more effectively.

Is it cheaper to run a generator on gasoline or natural gas?

Generators powered by natural gas are more energy-efficient and less expensive to operate than generators powered by fossil fuels.

Does propane last longer than gas in a generator?

When compared to gas-powered generators, propane generators have lower BTU output per gallon of fuel. When it comes to fueling your generators, propane is a more environmentally friendly option than gasoline.

Can stale gas be restored?

There is no cost-effective way to return gasoline that is as ancient as you’ll discover to its original homogeneous state.

Is seafoam a fuel stabilizer?

For up to two years, Sea Foam Motor Treatment stabilizes stored gasoline. Preventing gum and varnish buildup by adding Sea Foam to storage tanks helps keep gasoline from drying up and evaporating, while also preserving ignition vapors.

How long does ethanol-free gas last with a stabilizer?

A fuel’s shelf life may be extended by up to two years by mixing in a stabilizer. As long as you aren’t planning on keeping your ethanol-free gasoline for more than six months, it’s doubtful you’ll profit from adding a stabilizer.


It is possible your generator’s fuel will go bad if it is left inside the tank for too long without operation. If you plan on storing your generator for a long period of time, make sure to empty its fuel beforehand.

The “how long can a generac natural gas generator run?” is a question that has been asked by many. The answer to this question is determined by the length of time that the standby generator is left running, and how much fuel it uses.

NEXT UP: Whole-Home Generators vs. Other Generators

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James Sylvester
About James Sylvester

James S. Sylvester is an experienced OSHA Safety Supervisor with years of experience in the construction and oil & gas industries. He focuses on workplace safety, occupational health and safety systems. Learn more about James' here or connect with him on Twitter