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How Does Fuel Stabilizer Work?


Fuel stabilizer is some of the most inexpensive insurance you can buy when storing a car, truck or small-engined tool (like a lawn mower or snowblower) long term. It gives you the peace of mind of knowing that when you go to start an engine after it’s been sitting for several months, the gasoline inside its tank will still be fresh enough to fire up.

How, exactly, does fuel stabilizer work, and why do you even need it in the first place? Here’s a look at how this small bottle can save you from big headaches down the road.

Water, Water Everywhere

Gasoline is a blend of a number of different chemicals. Over time, it begins to break down, as it’s exposed to both oxygen and moisture from the air around it. Even if you store your vehicle with a full tank of gas to keep as much air out as possible, oxidation will still occur. This is especially true for modern gasoline that contains a high percentage of ethanol, which is hygroscopic, meaning it does a very good job of attracting and absorbing water. This only accelerates the breakdown of fuel.

On a long enough timeline — usually three to six months, depending on the quality of the gasoline, but sometimes quicker — the oxidation process will start to degrade gasoline to the point where it becomes a soupy, varnish-like mess that can clog your fuel lines and gum up your tank, pump and injectors.

Enter Fuel Stabilizer

gas canFuel stabilizer works to stop this oxidation and chemical breakdown from happening. By pouring it into your tank and running the engine for a few minutes to distribute it through the system, it functions partly as an antioxidant and partly by absorbing water before your fuel can do the same. The chemicals in stabilizer do their best to slow down the negative effects of long-term gasoline storage. It’s important to remember that this product can’t work miracles. If you’re storing a vehicle for more than a few years, you may want to investigate how you can keep fresh fuel moving through the lines (typically by regularly running through a tank on a specific schedule). For seasonal storage, however, it’s an excellent tool to have at your disposal.

You can’t turn “bad” fuel into “good” fuel by adding fuel stabilizer, but you can keep gasoline relatively fresh over a long period of time by introducing it at the beginning of storage.

Check out all the chemical products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on fuel stabilizer, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Morguefile.

Benjamin Hunting View All

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

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