Can a Chainsaw Gas Go Bad? (Things You May Not Know)

Chainsaws are quite useful tools for anyone who needs to do some serious cutting or trimming. However, most people usually don’t know about its fuel. One of the most frequently asked questions is can a chainsaw gas go bad?

The answer to this question is yes, a chainsaw gas can go bad. In most cases, the gas will produce a spoiled varnish-like odor. In addition, it will look murky and darker than the regular oil mix color. Under such conditions, the gas mix should never be used in a chainsaw.

How long does chainsaw gas last? In general, how long does it remain usable? Probably you are thinking about many questions like this right now. 

I’ve gathered all the information you need about chainsaw gas and its shelf life in this article to save you time and stress.

There are some interesting facts in it that you might not know, so I highly recommend reading it to the end. It’s time to get started, so let’s begin.

Can a Chainsaw Gas Go Bad?

Can a Chainsaw Gas Go Bad?

As we all know, gas is a mixture of oil and gasoline. The main function of this mixture is to lubricate the engine while it’s running.

However, over time this mixture can go bad and spoil. There are several reasons why this might happen.

One of the most common reasons is because of its exposure to air. When gas is exposed to air, it will start to oxidize and produce a varnish-like substance.

This varnish-like thing will then clog up the carburetor and prevent the engine from running properly.

Another reason why chainsaw gas might go bad is because of contamination. This usually happens when water or other foreign substances get into the gas tank.

Water contamination is particularly problematic because it can cause the gas to freeze and expand. This can damage the engine and cause it to seize up.

Foreign substances can also clog up the carburetor and prevent the engine from running properly.

How Long Does Chainsaw Gas Last?

The shelf life of chainsaw gas depends on how it’s stored. If it’s stored properly, it can last for up to 3 years. However, if it’s not stored properly, it can go bad in as little as 30 days.

We know that usually chainsaws use high octane fuel mix of 87 ratings. According to research, such a fuel mix has a maximum shelf life of around 3 months [1].

In contrast to 87 octane gas, the 93 octane fuel lasts up to 9 months which proves to be much more durable [2].

However, this doesn’t mean you should start using the 93-octane fuel in your saw right away. This is because your chainsaw engine may not be designed for it.

One of the most important things to remember is to keep the gas can sealed tight. This will prevent the gas from evaporating and going bad.

Another thing to remember is to store the gas can in a cool, dry place. Heat and sunlight can cause the gas to break down and go bad.

If you’re not sure if the gas is still good, it’s always best to err on the side of caution and throw it away. It’s better to be safe than sorry when it comes to chainsaw gas [2].

Adding fuel to a Stihl chainsaw

How do you know if your chainsaw gas is bad?

Next up, you might be wondering how to tell if chainsaw gas is bad inside your chainsaw fuel tank. Well, this is an interesting question.

Here are a few things that you will notice whenever the fuel inside the chainsaw tank goes bad.

The engine won’t start

The first thing that you will notice is that the chainsaw engine won’t start. This is because the bad gas has clogged up the carburetor and prevented the engine from getting the fuel it needs to run.

If you try to start the engine and it just won’t turn over, this is a sure sign that the gas has gone bad.

The engine will sputter and die

Another thing you might notice is that the chainsaw engine will sputter and die. This is because the bad gas isn’t burning properly and is causing the engine to misfire.

If you notice that the chainsaw engine is sputtering and dying, this is a good indication that the gas has gone bad.

The primer bulb isn’t working

The next thing that mostly happens when the gas is bad is that the primer bulb won’t work. The primer bulb is responsible for delivering fuel to the carburetor.

If you try to press the primer bulb and it doesn’t feel firm or doesn’t fill up with gas, this is a sign that the gas has gone bad.

There is a bad smell in the gas tank

As I mentioned before, chainsaw fuel that goes bad usually starts producing a pungent smell. This smell is usually like a mixture of vinegar and paint fumes.

If you notice this kind of smell coming from the gas tank, it’s a good indication that the gas has gone bad.

There is excessive smoke

The last thing that you will notice is that the saw will start producing unusual smoke in excess amount.

This happens because the bad gas isn’t burning properly and is causing the engine to produce more smoke than usual. If you notice this, it’s a sure sign that the gas has gone bad.

These are just a few of the things that you will notice when the chainsaw gas goes bad. If you notice any of these things, it’s best to drain the gas tank and get rid of the bad gas.

Adding fuel mixture to a husqvarna chainsaw

How Long Can You Leave Gas in a Chainsaw?

I have already mentioned the shelf life of a chainsaw gas but most people might still be wondering how long can they leave it inside the chainsaw fuel tank. 

According to Glen-McMillian (former mechanic of small engines and small engines operator) [4], a chainsaw gas will be good for a month or two.

However, if you leave it for a longer period such as over a season then you are begging for trouble. 

Let’s say you have put your chainsaw in your garage and that is already off over a season then you shouldn’t panic at all. There is still a way to fix things.

Under such conditions, you will need to run your chainsaw dry until it shuts down. After that put the choke on and pull the cord a few times. 

You have to make sure that there is not even a single drop of it left inside the tank.

After that, you can start it again and it will work like new. But of course, this method is not recommended if you don’t have to. The best way is still to avoid leaving gas in the chainsaw for a long time.

How do you drain gas from a chainsaw?

So you don’t want to follow the above method because it sounds too risky right?

Well, don’t worry because there is still another way to do it.

This method is much safer and easier.

The first thing you need to do is to turn the chainsaw upside down and let all the gas inside the tank come out.

You can do this by tilting the chainsaw until all the gas comes out.

Be sure to do this in a well-ventilated area so that you won’t breathe in too many fumes.

Remember it is just gas and not acid or something so you shouldn’t worry too much about it.

However, you need to tilt the saw in different directions to make sure every single drop of the liquid comes out.

Last Minute Thoughts!

So can a chainsaw gas go bad? Yes, it does if you leave it inside for too long. We have already discussed above that a chainsaw use mixed fuel and therefore, the fuel has a shelf life.

You need to make sure that you are using fresh gas all the time. This will help your chainsaw engine to run smoothly and last longer.

Even if by chance you happen to leave your chainsaw for too long then you should make sure that all of the bad fuel is out of the tank before adding a new one.

I hope you have not only enjoyed reading this article but also found some interesting information that you didn’t know before.

If you think my article was helpful please don’t forget to leave feedback. Also, make sure to share it with your friends and family too.

Thank you for reading and have a wonderful day!

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Jack Logan is a student of MS Global Navigation Satellite System who spends his free time researching and writing articles, many of which are geared towards helping people. His favorite power tools are miter saws and impact wrenches Read More About Jack