How Long Should You Leave In A Gas Generator?

Running a generator with old or contaminated gas can have a number of negative consequences for its overall health, performance, and usefulness.

How Long Can You Leave Gas In A Generator?

The span of time gasoline can be stored depends on factors such as the type of gas, how it is stored, and where it is stored.

It is important to note that gas will naturally degrade over time as a result of a process known as oxidation. The length of time, however, varies depending on the type of gasoline used.

In general, gasoline purchased at your local gas station will last one to three months. Other types of gas, on the other hand, have a longer shelf life.

Pure gasoline has a shelf life of up to six months. It differs from regular gas in that it contains no ethanol. This, however, does not prevent pure gasoline from oxidizing.

Because pure gas contains no ethanol, it oxidizes more slowly than ethanol-blended gas. When stored properly, this extends the shelf life to six months.

Owing to the effects of oxidation and evaporation, gasoline degrades and loses its combustibility over time. However, the process can be slowed if it is stored properly, which takes about a half year.

When storing gas in the fuel tank, ensure that the tank is filled to the recommended level. This decreases the amount of oxygen in the tank, limiting the oxidation process.

How To Extend The Life Of A Generator’s Leftover Gas?

Gasoline loses its capacity to combust over time, requiring your generator to need more fuel to create the same amount of power. The amount of money spent on fuel will rise as a result of this.

Some of the best ways to extend the life span of the generator are given below:

1. Fill The Gas Tank All The Way To The Top

When filling the tank of your generator with gasoline, try to fill it all the way to the top. Do not overfill it to the point where there is no room for air; this would be considered overfilling. Consult the user manual for the gallon rating of your fuel tank and use that value as your target volume.

As a result, there should still be some room in your fuel tank for vapors to expand and contract, but it should be filled. As a result, you don’t want to overfill or underfill your tank.

2. Avoid Using Ethanol Gasoline

As previously stated, ethanol has a high affinity for water and will absorb more of it while also oxidizing faster than ethanol-free fuel.

Some have reported that working with generator engines that run on ethanol fuel had poorer fuel lines than working with pure gasoline engines. Furthermore, the carburetor jets became clogged as a result of the increased moisture in the fuel.

Having said that, it’s important to note that ethanol-free gasoline is treated with a fuel stabilizer. A fuel stabilizer is added to gasoline to prevent it from reacting negatively to oxygen and oxidizing.

3. Turn Off Your Generator’s Fuel Valve

It is critical to turn off the generator’s fuel valve whenever it comes to a halt. This is a step beyond simply turning off your generator’s kill switch.

It is critical to turn off your generator’s fuel valve and then let it run until it naturally comes to a stop. After you turn off the fuel valves, your generator will run for a few minutes, consuming all of the fuel in the fuel lines as well as the fuel in your carburetor.

Additionally, ensure that the fuel tank or fuel container used to store gas has an airtight cap. This will further reduce the amount of oxygen entering and the number of fumes exiting.

How Can I Tell If My Gasoline Is Contaminated?

Gasoline oxidizes and loses combustibility as it sits in your generator fuel tank or storage tanks, eventually becoming stale. You can look for several signs of bad gas in the generator.

Because gasoline, particularly ethanol-blended gas, loses its ability to combust as it ages, the generator will have difficulty starting. Furthermore, your generator will sputter, knock, and make unusual noises even when it is supposed to run smoothly.

How Long Can A Portable Gasoline Generator Run?

If you’re using a gasoline-powered portable generator, you’ll have to stop it from time to time rather than run it continually.

Never add gasoline to a gas generator while the engine is operating. It may appear simple to add gas, but it can be extremely dangerous and result in a big fire.

When your generator is running, it can grow very hot, and little spills or even gases could start a small fire, which could soon spread to the generator’s fuel tank or the tank you’re using to replenish.

Before adding more fuel, it’s a good idea to turn off your generator for 5 to 10 minutes.

You can’t truly run a gasoline generator continuously beyond the typical runtime. Depending on the size, type, and amount of electricity you’re using, this could take anywhere from 6 to 12 hours for most gas generators. It’s worth noting that some alternatives are lengthier than others.

Related Questions

Is leaving gas in a generator a bad idea?

Because untreated fuel can deteriorate when exposed to the outdoors, it may not be able to power the generator when you need it most. While the generator is in storage, the gasoline can cause a lot of harm to various sections of it. As a result, leaving untreated fuel in the generator isn’t an option.

Is it possible for gas to spoil in a gas can?

If stored in a sealed and labeled metal or plastic container, pure gas will decay and lose its combustibility in three to six months due to oxidation and evaporation. Blends of ethanol and gasoline have a shelf life of two to three months.


Leaving gas in a generator for longer than 6 months is generally a bad idea. This will eventually wear down your generator due to corrosion and may cause carburetor clogging, so make your decision carefully.


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