Generator Jungle
Fuel Stabilizer

Written by Chris on March 21, 2023

Updated on: 20 July 2023 

Fuel Stabilizers – All You Need to Know

Fuel Stabilizers (Gasoline) – Introduction

Here we aim to give you in a simple and concise way:

  • What is gasoline?
  • What happens over time if gasoline is not treated (even if it is stored in optimal conditions)?
  • Should you drain your tank as well as the carburetor?
  • What fuel stabilizers are.
  • Why you should consider using a fuel stabilizer with your portable generator.

And, finally, offer you a selection of what looks to be some of the best fuel stabilizers out there according to the people who have used them.

What is Gasoline?

Gasoline is just one of the products refined from crude oil. Whereas crude oil is often referred to as petroleum, the term embraces a wider range of derivatives, which includes all liquid, gaseous and solid forms of hydrocarbons found in the Earth’s crust.

Crude oil is the liquid component of petroleum and is pumped out of the ground at a well-head. It was formed from dead organisms that were buried millions of years ago and subjected to intense heat and pressure. Its origin is why it is classified as a “fossil” fuel.

Crude oil can vary from having a low viscosity, commonly known as light crude to being thick and tar-like, commonly known as heavy crude. The light variety is more valuable because it is easier to extract and refine, and produces a higher percentage of the more valuable parts, such as gasoline and diesel, than heavy crude.

Gasoline is among the most common of the various components that make up crude oil. It is produced by a process of fractional distillation, defined as the separation of a mixture into its component parts, or fractions, by repeated distillation at different temperatures. Each of these fractions is also made up of multiple substances. In relation to the gasoline fraction, this separates at between 100 and 150 degrees centigrade as a clear liquid of between 8 and 12 carbons long.

For those interested in learning more about the process, the following video demonstrates fractional distillation in a lab environment.

Gasoline in its purest form has nowadays become rarer in the US as concerns over its harmful emissions impacting the environment have grown.

One way to reduce fuel emissions is to add ethanol, a renewable fuel produced mainly from the starch in corn grain, but also from other plant materials. These are collectively known as biomass. In the US the vast majority – more than 98% – contains a 10% ethanol (E10). There are also gasoline variants that have 15% (E15) and up to 85% (E85) ethanol. The addition of ethanol also has a positive effect as it increases the octane rating of gasoline, which is a measure to indicate how the fuel prevents “knocking”, or cylinder clatter, when ignited in a mixture with air in an internal combustion engine.

In the case of portable generator engines, some manufacturers advise owners to use ethanol-free gasoline of at least 87 octane rating, while others recommend the use of a similar gasoline, but with no more than 10% ethanol (E10). If you are someone who believes in the use of ethanol-free gasoline, this website collects and publishes information on gas stations in the US and Canada that still serve this product.

What happens to gasoline that has not been treated with a stabilizer?

Good quality gasoline should remain stable almost indefinitely if stored properly. But for the most part, gasoline is rarely stored in the kind of ideal conditions necessary to avoid deterioration. Such condition would include an airtight container and a constant cool temperature, but this too only serves to delay the inevitable.

Under more common circumstances, when gasoline is left standing for around 30 days or so its components, including the added ethanol, begin to oxidize at different rates, absorbing moisture in the air. Often this is described as fuel “going bad” or becoming stale, smelling like varnish, and forming a sticky gel-like substance. This substance sinks to the bottom of the fuel tank where it is the first to be drawn into the fuel system causing it to gum up completely. Ethanol-free gasoline also suffers from the same kind of oxidation, though the process is slower. But eventually it will also gum up the fuel lines and carburetor as well. In the case of fuel containing ethanol its more technical term is Phase Separation, which is more pronounced the colder the weather. For a practical demonstration of the process, take a look at the following video.

Should I drain the gas tank as well as the carburetor?

To prevent problems associated with stale fuel, draining a gas tank prior to long-term storage is a recommendation that is sometimes made. However, you should be aware that gas tanks can develop corrosion if empty, and if left for long enough this can cause permanent damage. The corrosion is caused by a combination of factors, including condensation from which moisture begins the corrosive process and causes rusting.

Therefore, while you may be tempted to drain everything, consider the potential benefits of keeping the tank filled with stabilized gasoline as a practical alternative, especially as fuel stabilizers are relatively inexpensive and you only need to add small amounts for them to be effective.

What is fuel stabilizer made of?

Basically, a fuel stabilizer is a formula containing antioxidants and lubricants that bond with gasoline to repel water and reduce evaporation. Each brand has its own proprietary formulas, but in general the results will be similar.

Why do you need to use a fuel stabilizer with your generator?

So, as you can appreciate, the main reason why it is advisable for you to use a fuel stabilizer with a portable generator is how infrequent the generators are, or have to be, used. While not in use, they are put into safe storage, often with gasoline, or its residues, in the fuel system, including the carburetor, fuel lines and fuel tank. Over time the gradual breakdown of gasoline mentioned above will be taking place, usually starting after some 30 days.

Once this occurs, partial or complete fuel starvation will either cause severely uneven running of the engine or prevent the generator from starting at all. It will remain inoperative at least until some major maintenance has taken place to clean the carburetor, fuel lines, and the fuel tank itself. And in some cases, it may require the replacement of any or all of these parts.

So, while it may not be possible to completely halt this deterioration, it can be slowed down considerably by the addition of a fuel stabilizer. Typically, a fuel stabilizer will ensure that your gasoline remains in a good condition for up to 12 months.


Article by Chris

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