Opinion: Do Fuel Stabilizers Work?

Maybe you plan on riding your motorcycle all winter long. If that’s the case, I salute you. Given the current travel restrictions, it doesn’t look like I’ll be doing much riding this winter. Even when I flew to San Diego, CA to avoid winter a couple years ago, it still managed to find me.

A few weeks ago I mentioned that I’d be tucking the Thruxton in for a long winter’s slumber after its first service. The process would include the annual routine of hooking up a battery tender, topping up the tank, and finally, adding quality fuel stabilizer. One commenter rightly questioned this rationale. A video recently shared on FortNine’s YouTube channel has been making the rounds which questions the entire validity of this practice. . I was admittedly negligent by not mentioning the specific gas I added or brand of stabilizer I used, because it matters.

In the current climate of fake news and misinformation, it is important to question everything. Tire manufacturers will be the first to tell you that you need winter tires, but of course some are better than others. And, of course, the companies that make fuel stabilizer will tell you that your motorcycle needs their products in order to prevent serious damage. But as the aforementioned video demonstrates, some could actually do more harm than good.

Modern gasoline contains various levels of ethanol, which absorbs moisture which leads to corrosion. This begs the question, why add ethanol at all? Well, as the video states, it boosts octane numbers and burns more completely, while also helping support domestic farmers and reducing reliance on foreign oil consumption.

Fuel stabilizer is hydrophobic (repels water molecules), which is intended to mix with the gasoline in your tank, preventing it from picking up H20. In theory. Using a control of gasoline with 10 per cent ethanol (no stabilizer) compared to the same fuel mixed with six different kinds of stabilizer, humidity is added for thirty minutes to measure how much moisture is absorbed. Some of the stabilizers marginally prevented this, others did nothing and two even attracted more moisture than not using stabilizer at all. They had one job!

When left to their own devices fuel additives can settle to the bottom of your tank over time, clogging up your carburetors or fuel injectors. They (along with the moisture gathered) will reduce combustion, so a water-soluble fuel like methanol is added to improve flammability. The next test measured how each stabilizer faired in this area, again, with varying results.

The next consideration is something that us Canadians especially need to consider. Not everyone is lucky enough to have heated storage, so if your fuel stabilizer is attracting moisture rather than repelling it while sitting in a cold garage or shed then the fuel in your tank could actually freeze. I don’t think we need to explore why that isn’t a good thing.

Fuel stabilizers also have antioxidants to prevent corrosion in your tank and various parts of your fuel system. Again, some of the stabilizers tested provided fair to negligible results, while others were so bad it was cringe-worthy.

Fuel stabilizers are used to reduce moisture and prevent oxidation, but if they do the opposite, then why bother? Each of these elements are intensified the more ethanol is in your gas. If your bike will be sitting for months on end in a cold climate, it stands to reason that you should top up your last tank of the season with ethanol-free gas. And if you don’t have a heated garage, why not bring your motorcycle into the house?


  1. Another fun video from FortNine. I always enjoy Ryan’s work. As a chemist that has spent a few years working in the lab of an oil refinery doing product R&D and process control I see a couple of problems with the methodology used in the video. The most glaring is that it is mostly based on the assumption that the addition of ethanol in today’s gasoline is the sole reason that gasoline degrades and causes problems during long-term storage. Ryan misses the main point of fuel stabilizers, which is to prevent oxidation of petroleum molecules. None of the stabilizer products claim to protect metal fuel tanks.

    Petroleum hydrocarbons react with oxygen and ozone resulting in the formation of polymers that are typically called “varnish” when they show up in fuel systems. These polymers are not very soluble in gasoline and settle to the bottom of carb bowls and clog filters and injectors.

    Varnish and foul-smelling old gas are not as much a problem today as they used to be, with or without adding stabilizers. In the USA, and I assume Canada, we can thank pollution regulations for the improved stability of gasoline. Varnish causes problems in fuel systems that result in more pollution. It was back in the early and mid-1990s that fuel regulations began being implemented to reduce ozone and SMOG. One of those was EPA’s 1996 deposit control additive program meant to ensure all gasoline contains additives to limit formation of varnish deposits. These additives are a combination of detergents and anti-oxidants. Today’s gasolines are much more stable with age than they used to be. One might argue that the need to add a stabilizer to gasoline is no longer needed in much of the world.

    Ryan and many others believe that filling the tank with non-ethanol gasoline is the solution for long-term storage. With or without ethanol, all gasoline in the developed world is required to contain oxygenators to reduce pollution. So, ethanol free gasoline contains a different oxygenating chemical, you just don’t know what it is.

    There is no safe and quick way to test the performance of fuels stabilizers. Oxidation takes time and if you try to rush it with flammable liquids you’re literally playing with fire. A real test would be a set of vented containers with various fuel stabilizers added to gasoline and let them sit for a year. After the year is up give them a sniff and pour them through a paper filter to see how much, or how little varnish is formed.

  2. You sould buy a Q-RAY BRACELET. I find it hard to believe that running super fuel and adding SEA FOAM to the gas is a bad thing. Petrol deteriorates as soon as it leavs the refinery.I have had zero issues over the last 40 years.Just emptied and re filled my 1984 KZ 750. The fuel [ treated ] was in there for 18 months and looks and burns good. Also pulled carb bottoms and super clean.

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