Can You Add Fuel Stabilizer To Old Gas?

Can You Add Fuel Stabilizer To Old Gas?

If you have stored your boat for a long time you may end up with a tank full of old gas. While sometimes it’s unavoidable, leaving fuel in the tank for long periods is not advisable. 

You may have heard that it’s possible to fix this situation with fuel stabilizer, but can you add fuel stabilizer to old gas? 

What Is A Fuel Stabilizer?

A fuel stabilizer is a type of pour-in additive that you can add to your fuel tank. Its purpose is to slow down the oxidation of fuel in order to extend its life.

These stabilizers are typically a mix of lubricants and antioxidants which are designed to bond with the fuel. 

The stabilizer also repels water and serves to limit the evaporation of the fuel and the formation of winter ice. Occasionally stabilizers will also contain alcohol which mixes with the water to create a mixture that will burn. 

The need for fuel stabilizers has come about due to the change in the composition of gasoline in recent years. 

Different formulations in past times meant gasoline didn’t really have this problem, but now most gas contains at least 10% ethanol.

This arguably makes the fuel more susceptible to breaking down over time, hence the need for a stabilizer. 

Does Fuel Have A Limited Life?

There are lots of reasons why you might leave gas sitting in your vessel for long periods of time.

It may be that you are not using your boat as much as you would like, or perhaps your health or job are preventing you from spending more time on the water. 

Whatever the reason, unfortunately, it is true that fuel has a limited life. The exact life of the fuel will depend on its composition.

For example, pure gasoline which is petroleum based can last for 6 months before you will see any sign of degradation from oxidation. 

On the other hand, fuel that is a blend of petroleum and ethanol has a much shorter life and will begin to degrade after just 3 months. 

The reason for the difference between the two is that pure gasoline doesn’t absorb water and so can avoid contamination from moisture.

A gasoline that contains ethanol will easily absorb moisture and so this leads to contamination. 

Can Fuel Stabilizer Restore Old Gas?

When you have old gas in your boat you may wonder if adding fuel stabilizer will restore it. Unfortunately, the answer is no, it’s not possible to restore old gas to its original state. 

This is because the chemicals that have been lost cannot be reintroduced to the gasoline via the fuel stabilizer. However, adding a fuel stabilizer to old gasoline can prevent further degradation of the fuel. 

It is best to use fuel stabilizer in fresh fuel as this is where they will be most effective. The rate of oxidation and evaporation will be slowed down, extending the life of your fuel. 

This can help to maintain the fuel in good condition for between one and three years depending on the fuel stabilizer that you use. 

So although you can add fuel stabilizer to your old gas, that doesn’t mean that it will restore the effectiveness of the gasoline. 

What To Do With Old Gas In Your Boat?

If your boat has been inactive for a long time, and you are concerned about the age of the gasoline in the tank then there are things you can do. 

Siphoning out the old fuel is the best option and store it in an appropriate container until you decide what to do with it. 

Of course, you may not want to just dispose of it given the price of fuel these days, so you can use it in a vehicle that you run on a regular basis.

When you do add the old gas to a vehicle it’s best to add it to a partially filled tank that has fresh gas in it. 

When you refill the gas tank of your boat with fresh fuel you should then add some fuel stabilizer to it. 

Does Old Gas Cause Engine Problems?

Can You Add Fuel Stabilizer To Old Gas?

When gas degrades after it has been sitting in your boat for a long time there are a few reactions that are going on. The gasoline reacts with air, water as well as catalytic metals, and these all add to the degrading process. 

Although you won’t be able to see these reactions and their consequences, the fuel will likely have darkened in color.

It will also likely have gone through phase separation when the gas and the alcohol separate in ethanol blend fuels. 

If your gasoline has gone bad then it will have the potential to cause problems for your engine. 

One of the first things you may notice is that the engine may be difficult to start. When you do get it running it may sound quite rough. Bad fuel can also mean that the engine may struggle to idle. 

How To Tell If There’s Bad Gas In Your Boat?

So how can you tell if the gas in your boat has degraded and is now bad? There are actually a few telltale signs. 

The first sign is the smell of the fuel. Fresh gasoline has a very distinctive smell and is easy to recognize.

If the fuel in your boat tank has oxidized and degraded it will have a different smell that is more akin to varnish. Once you smell it you will understand what we mean. 

Fresh gas should be transparent but fuel that has gone bad will be a yellowish color. It may also have separated in the tank and have separate layers of water and a thick gummy substance. This is called phase separation. 

Bad fuel will also cause engine problems such as spluttering and problems starting and idling. 

Final Thoughts

We hope that you have found this guide to whether you can add fuel stabilizer to old gas helpful and informative. 

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