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The Best Ethanol Fuel Treatments

Written by Anthony Roberts / Fact checked by Jonathan Larson

Unless you are granted the rare privilege of having a consistent source of ethanol-free fuel, you always need to be cautious of the possible long-term issues that ethanol will inflict on any vehicle that you own. For many people, especially Americans, it’s unavoidable, like death and taxes as the old saying goes. We get that it’s environment-friendly, but its disadvantages can be tough on the wallet.

best ethanol fuel treatment

What’s good is that there’s nothing the best ethanol fuel treatment can’t handle. From an engine misfiring, running slowly and idling to low fuel longevity, it didn’t take long for me to become a believer in the wonders of these additives and stabilizers.

Care to try them out yourself? Then, read my review of ten products that stood out to me in all the time I started using fuel treatment for ethanol below.

<strong>Top 1</strong>

STA-BIL 22240

+ Excellent fuel-keeping ability
+ Works best on small motors
+ Great fuel cleaner

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<strong>Top 2</strong>


+ Works well for a lot of vehicles
+ Remarkable fuel keeping
+ Improves engine performance

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<strong>Top 3</strong>

Sea Foam SF-16

+ Easy to apply most of the time
+ Excellent fuel cleaner
+ Good stabilizer for small motors

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Top 10 Ethanol Fuel Treatment Reviews

1. STA-BIL 22240 Marine Ethanol Treatment

STA-BIL 360 is a top boat fuel treatment because it anticipates the average boater’s habits and addresses plenty of ethanol problems at the same time.

Despite its obvious strengths, I can’t back the brand’s claim that it makes fuel last up to a year. That being said, the most I’ve kept my vessel idle is 8 months. My STA-BIL-treated gas still managed to efficiently power my Yamaha fishing boat for a day in spite of the length of time that I chucked the rest and did a fresh, full refill. I’ll take that perk any day.

This brand will always be my go-to for keeping fuel fresh for a long time for this reason alone. That’s assuming you won’t be taking your boat out for a long period since I’ve found that it does its magic better if it isn’t disturbed every now and then.

On the whole, it works best on small engines and outboards, in my case. I also apply it to my lawnmower every once in a while to ensure it starts smoothly every time. I can also say that it works great as a fuel cleaner, since I don’t encounter any ethanol issues on all the motors that I’ve used it on.

I have only one small complaint about the bottle design. I wish I could pour it directly without the worry of any spillage occurring. I kind of hate that I sometimes have to use a syringe just to keep this from happening and to ensure accurate measurements.
  • Excellent fuel-keeping ability
  • Works best on small motors
  • Great fuel cleaner
  • Delivers most of what it promises
  • Bottle design needs improvement
I’m well aware that no ethanol fuel treatment or fuel additive should be considered as a cure-all for ethanol issues. Nor can phase separation be ever assured with every use. Nonetheless, what I can say is that this product made a big difference in how I now seldom encounter the performance issues I used to have with my boat’s outboard motor and other small tools the moment I started applying this.

2. STAR BRITE Star Tron Enzyme Fuel Treatment

Can be used on most vehicles, cars, motorcycles, and boats, Star Tron’s versatility is only further punctuated by its myriad benefits found in ethanol treatments.

The first thing that I need to emphasize about this product is its outstanding fuel stabilizing ability. It’s way up there with STA-BIL as far as this feature is concerned. My father agrees with me on this as he uses it regularly for his Boston Whaler.

He takes it out but tends to keep it fueled for an entire year. I can attest that his boat still runs and starts well even after the fuel has stayed dormant for more than a year. It may not be two years as the brand claims but that’s still a rare feat.

Moreover, a friend of mine used it on his pontoon boat, which he didn’t touch for a whopping three years! He couldn’t take the old gas out so he just applied this and refueled the boat with fresh 91 supreme gas. It started cleanly and worked as good as new for the entire day we spent cruising on it.

I didn’t buy the mileage-boosting claim at first having used my fair share of products that fell short in that regard. But, when I started seeing notable gradual increases in my MPG, topping at about 2.5 extra miles for my car, this became an instant favorite. I’ll take those seemingly marginal mileage jumps any day considering I never change my driving habits and the fact that it helps me save more in the long run.

To me, almost all vehicles and lawnmowers that I apply this to run better, which is a good sign that it tackles the usual ethanol issues. It’s not hard to hear the difference based on the sounds alone. For that, it already wins in value for money.

It would be perfect if it included a measuring tool of some kind. It will save me time and effort, after all.
  • Proven to boost mileage and fuel efficiency
  • Works well for a lot of vehicles
  • Remarkable fuel keeping
  • Improves engine performance
  • Well worth the money
  • Needs a measurer
This product’s combination of benefits is hard to top. It sets the bar high for the right ethanol treatment for boats and other vehicles.

3. Sea Foam SF-16 Motor Treatment

As far as an ethanol fuel additive is concerned, it’s hard to not include a product that’s been around for decades and has gained the trust of hundreds of mechanics. Sea Foam is one of the rare few that automatically earns that recognition.

Where this product is applied, ethanol issues almost always take a backseat. I use this on boats, cars, lawnmowers, and leaf blowers, especially if I have no choice but to use ethanol-laced fuel. I may not get the same stellar engine performance afterward, but I can say as much for the majority of them.

This is coming from someone who knows what poorly running engines sound like as a result of ethanol. It solves the issue right away and keeps it from coming back for good. Is it any wonder why many people stick with this product?

It works better as a fuel cleaner than a stabilizer, in my opinion. I just pour the right amount in a tankful of gas and it quickly clears up deposits in vehicles and gadgets that work well with it. But for most small engines, I admit it’s a better stabilizer because it still lets my leaf blower run smoothly after 7 months of storage.

Its only real flaw is that it doesn’t take its versatility all the way. For instance, it doesn’t work its magic on other outboard brands that I own.
  • Can be used on a variety of vehicles and home tools
  • Easy to apply most of the time
  • Protects most engines from ethanol problems
  • Excellent fuel cleaner
  • Good stabilizer for small motors
  • May not work on certain gas or diesel engines
Sea Foam may not work on all engines. Nor can it always deliver some of its powerful advantages. However, many in the automotive and boating industries are without a doubt glad that there’s always this solid additive for small engines to avoid problems with ethanol readily available in the market.

4. STA-BIL 22275 Ethanol Treatment

With its name and brand reputation, STA-BIL 360’s special ethanol treatment solution may seem like one of those products that easily earns a spot here. Ultimately, it’s the difference it makes that seals the deal.

What exactly is that difference? To me, it’s the versatility. It addresses ethanol issues as great as Sea Foam yet still guarantees your gas won’t be rendered useless by the same chemical in less than a month. I could just as easily substitute this for the said fuel cleaner to make sure my small engines stay unblemished by ethanol.

While I can get more out of other STA-BIL products when keeping my fuel fresh for a long time, this one can still do a fine job in that it works well for gas or diesel you’ll be storing for no more than 6 months. That’s the average for all the boats and cars I’ve used it on. With that said, I feel it works best as a fuel cleaner and engine performance booster.

I have a buddy who attests that this gives him a whopping 50 miles more per fill-up, which is nothing short of outstanding. As for me, I can safely say that it does give my Subaru at least a 10 to 15-mile increase. In my boats, the MPG increase is marginal, around 3 miles at most, but I can’t complain since I rarely get this perk for my outboards with the other additives that I use.

Overall, it’s on-par with Sea Foam, and I won’t hesitate to get this if the latter isn’t available. As for other cons, I also dislike the fact that it’s pricey.
  • Above-average fuel stabilizing
  • Proven to boost mileage
  • Improves engine performance
  • Overall excellent fuel cleaner
  • Pales in comparison to a few STA-BIL products
  • Pricey
This product is another reliable offering from a well-known brand that has its own unique mix of benefits. At least, my first-hand experiences over time outlined in this STA-BIL ethanol treatment review have revealed as much.

5. Lucas Oil 10576 Ethanol Fuel Conditioner

Economically priced and delivers no-nonsense results consistently, this Lucas Oil gas additive for ethanol effortlessly gets an A+ as a fuel system cleaner and for helping engines run the way they should.

I’ve seen the effects of this fuel conditioner on my cars, boats, a buddy’s jet ski, and other simple machines, like lawnmowers, and that should give you a good idea of its versatility. Almost all have two common denominators in their post-application results: better overall performance and smoother starts. I think that’s solid proof of how effective this is as an ethanol buster.

I use E85 gas on my cars. After cleaning and lubing the injectors with this, I noticed a marked improvement in deceleration. It’s much more responsive now after I brake and, more importantly, it took care of the bucking issue I had with my Evo X. It’s the only treatment I did for it, so I’m certain it’s the one responsible for addressing the issue.

I’ve been using this regularly for 3 years. In all that span of time, I get close to zero ethanol issues. I’m not too sure if it deserves all the credit for that, but I’m fairly sure that it’s largely responsible for these conducive results.

Unlike others who use this as an ethanol fuel stabilizer, I think it would be pushing it if I say it keeps my fuel fresh for as long as other products out there. I’d stick to cleaning and engine protection when using this conditioner.
  • Proven to work on gasoline-powered boats, cars, jet skis, and other applicable machines
  • Improves performance and helps engines start smoother
  • Budget-friendly
  • Provides active protection against ethanol damage
  • Excellent value for money
  • Doesn’t keep fuel from getting stale that well
I cannot think of a more cost-effective brand that serves as an ever-reliable ethanol treatment for gas than this product. Highly recommended if your budget’s a little tight or if you have an old car that can’t handle ethanol.

6. STAR BRITE Star Tron Enzyme Fuel Treatment

This version of the classic Star Tron enzyme fuel treatment maxes out its protective capabilities. You expect both outstanding fuel stabilizing and long-term protection from clogs from this.

I’m going to go right ahead and say what I love about this product. It delivers what it promises. Two years of guaranteed fuel freshness. At least, I can say as much for my old fishing boat’s Mercury outboard when I had no other choice but to take a lengthy boating break after an accident broke my hip.

It started cleanly on the first pull-start. No rough idling or gumming whatsoever from the moment I left it running for 5 minutes until when I started cruising. I depleted the entire tank for one day of fishing and re-filled it with a fresh batch of fuel and poured a bit of this additive. Easy as pie usage if I may say so.

I no longer encounter any clogging issues in the majority of my small engines if I apply this to them. If that isn’t a hallmark of a far superior, if not ideal, fuel stabilizer and cleaner then I don’t know what is. This stuff won’t restore old fuel but it clears gunk and keeps any fuel you treat with it as good as the day you bought it.

I’m not praising its price tag anytime soon, though. Also, I admit there is a minor con in that this product only works best on small engines.
  • Keeps fuel fresh for a long time
  • Easy usage
  • Great in addressing idling and gumming problems
  • Protects from clogs
  • Removes buildups
  • Pricier than other good stabilizers
  • Benefits limited to small motors and engines
I’m of the opinion that this trumps STA-BIL in fuel stabilizing, and I bet I’m not the only one who thinks so. I’d easily choose this over that brand if I’m aiming for a year or two of storage.

7. LUCAS LUC10013 Fuel Treatment

LUCAS fuel treatment is one of those products that have a well-founded reputation for delivering the results it promises. To me, it’s as simple as getting that much-needed peace of mind with an ounce of this ethanol treatment for every 5 gallons of fuel.

There’s a low but still noticeable MPG increase of, on average, 1 extra mile when I use it on most of my land vehicles, which happens to be a Toyota Tundra and another family pickup. Both already have plenty of mileage and are a bit on the old side. That being said, I think it benefits cars with older engines, at least 10 years ago or more.

This is because a workmate of mine who owns a 2016 Camry said that he tried it out but didn’t notice any notable improvements. Others report getting up to 10% of fuel economy, which I bet is very much plausible. I’m going to have to try it out on other diesel and gas-powered vehicles to know.

I continue to use it as a way to repel fuel injector problems and keep the engine running good as new. That’s adequate considering it’s obvious that I’m only extending the life of the engine in general. I can’t say as much for the majority of other fuel treatments I’ve tried.

With my ratio of application, I’m basically getting remarkable 8 to 10% cost savings in fuel alone, and that’s not considering the protection that essential parts like injectors and fuel pumps enjoy. I’m sure that I’m saving a lot since these parts are prone to wear and tear courtesy of everyone’s good, old buddy ethanol.
  • Decent mileage and fuel economy improvements
  • Ideal for preventive maintenance
  • Cost-effective and great value for money
  • Keeps gas and diesel engine running at peak condition
  • Minimal benefits for vehicles with new engines
For older cars, this fuel treatment is a godsend. Overall, it’s great for motors that can’t handle ethanol well.

8. K-100 K100-G Fuel Treatment & Additive

Ideal for phase separation and as a fuel cleaner, almost anyone who tries out K-100 would undoubtedly discover how much of a gem it is.

I’ve tried this out on a Yamaha outboard, lawnmowers, snowblowers, and the only motorcycle I own. While I’d refute the brand’s claim that it “eliminates water”, I can say that this is one of the top-tier fuel treatments for phase separation issues. After all, it doesn’t eliminate water as much as it aids the engine in burning it off.

The mileage boosts I get from it is what ultimately convinced me of how terrific this product is. I can report as much as 30 extra miles with an application of 10 ounces per 20 gallons. That’s the exact capacity of my 2008 Infiniti, and all I can say is that the mileage meter doesn’t lie.

I can also say the same for the motorbike that I use, especially if it guzzles down ethanol-rich fuel regularly. It gives me at least 10 additional miles and the motor sounds like music to my ears every time I take it out for a ride. Not really much of a biker, but it makes a clear difference in my opinion.

As for my outboard, I’m glad it took care of a lingering starting problem it had. It starts alright but the motor dies after about 15 seconds. I tried K-100 on it and let it sit overnight. The next day I gave it the old pull-start, and the issue never reared its ugly head from then.

However, it has a quite lofty price tag. Also, I wish it made life easier for bikers, who happen to be its regular users, by including a funnel for easier pouring.
  • Best for addressing phase separation
  • Remarkable mileage boosts in cars and motorcycles
  • Improves engine
  • Versatile
  • Pricey
  • Could use a funnel for motors
Your standard ethanol additive in gasoline can rarely match the mileage boosts imparted by this fuel cleaner. To me, it’s already a winner with that sole benefit.

9. B3C Fuel Solutions Ethanol Fuel Treatment

Any product that can confidently state that it functions as a “Mechanic in a Bottle” can readily turn a lot of heads. Considering my positive experience with it, I can attest that it walks the talk.

It wonderfully serves as a solid solution to the 2-stroke and 4-stroke outboard problems that I usually get. Sure, there’s always Sea Foam that can almost magically dispel those idlings and sputterings. Even so, this is a neat alternative to have, especially if stocks are running short. You can always rely on this treatment for your ethanol issues.

I won’t hesitate to use this on anything with a carburetor, as long as its fuel is compatible, that is. It took care of a clogged carburetor issue that my generator has been having for a good portion of a year, and this was the first fuel cleaner that I used which effectively cleared up the buildup. I’m glad to share that the generator’s running in tip-top shape now.

Almost any vehicle or machine that has sat idle for a long time should, at least, be given this before use. I can compare the performance of my untreated and treated snowblower. The former’s is atrocious, to say the least.

Considering the price, bottle contents, and the recommended doses per gallon of this product, it’s quite costly. Still, I get what I pay for so it’s a better deal than treatments from other lesser-known brands.
  • Suitable for outboard motors and generators
  • Solves sputtering, idling, and rough starts
  • Cleans carburetor buildups
  • Great for restoring the performance of small engines
  • Costs more
Is this the top-rated ethanol treatment for small engines? I’m of half a mind to say yes.

10. Opti-mizer Ethanol Fuel Treatment Stabilizer

I feel that this stabilizer isn’t getting the recognition it deserves. It works great on 4-stroke motors, and if you’ve been having a hard time looking for an ethanol fuel treatment for those types of engines, I highly recommend you give this a try.

I’ve tried this fuel treatment out on Mercury 2-stroke outboards, a Yamaha 4-stroke outboard, a riding mower, and an ATV. I can say that I get the best results in 4-stroke engines. By best, I mean that it keeps the engine running cleanly and almost as good as new.

This advantage isn’t as pronounced in the other motors and vehicles that I mentioned. However, the fact that I don’t encounter the usual tell-tale signs when starting them serves as a good hint that it’s at least exerting a positive effect to some degree. I think it’s a great carburetor cleaner for this reason.

I’ve used this to keep the fuel of my riding mower and boats fresh when I won’t be using them over the winter. The longest I’ve kept them idle is 6 months, but I bet it keeps fuel from going stale for longer than that. My 4-strokes don’t cold start and display any of the common snags and slipups once I started using it on them.

The 4-stroke limitation serves as my main gripe with this fuel stabilizer. I understand that they have a separate product for it, but a lot of brands manage to formulate a fuel stabilizer for ethanol gas that can accommodate both 2-strokes and 4-strokes. It’s not cost-effective if you have other engines to treat.
  • Outstanding benefits are limited to 4-stroke engines
Its focus on small 4-stroke motors alone imparts this Opti-mizer’s value. I challenge you to name other brands that can deliver the same results for the said motor type.

Buyer’s Guide


Ethanol fuel treatments and fuel stabilizers are sometimes used interchangeably, but in essence, they may differ in their purpose. You have to know what these differences are before deciding to choose which product to buy.

Essentially, ethanol fuel treatments are types of fuel stabilizers that lean more toward engine performance rather than fuel storage. It’s more about prolonging the engine’s life than keeping fuel at its best. But, that doesn’t mean that they’re entirely devoid of benefits related to fuel longevity. Brands formulate their solutions with overlapping advantages in mind, after all.

It’s simply logical for you to opt for products that solve that particular problem. Specificity and compatibility, therefore, should be your main priorities. You should aim, for example, to choose products marketed as an ethanol gas treatment for small engines then read the user feedback about it.

Key signs of good ethanol treatments include excellent fuel system cleaning and notable engine performance boosts. It should be able to take care of phase separation and break down buildups of sludge that spell ethanol damage for most engines.

Be mindful of the types of fuel and motor each product is compatible with. Whether it’s E85, E10, or other diesel and gasoline available, you should ask the manufacturer about its suitability. Even the age of your motor should be considered.

Unless you’re switching from ethanol to non-ethanol, knowing what ethanol treatment to use would only do your engine and your wallet a load of good.

What is the Top-Rated Ethanol Fuel Treatment

To me, STA-BIL, Sea Foam, and Star Tron are the no-brainer options. Star Tron’s specially-formulated Enzyme Fuel Treatment tackles ethanol fuel issues head-on, and it has hundreds of satisfied customers who can back up its claims. The other two are also go-to options for addressing many ethanol problems, besides imparting a host of other benefits.

Even if I highlighted those three, I wouldn’t sleep on the other brands and products featured here. They’ve delivered satisfactory results in beating ethanol, even though they’re not as well-known.

How Do Ethanol Fuel Problems Affect the Fuel System


You don’t need to look further than the term “phase separation” to know how ethanol damages engines and motors. Ethanol tends to absorb the water naturally found in gasoline and diesel. This results in the said separation in the ethanol-water mix.

Any fuel that has completely undergone phase separation has a higher chance of damaging integral parts of the engine and fuel system, like the carburetors and injectors, to cite a few. If this is the case, the fuel would be unusable and would have to be drained to keep the fuel system running.

Other issues include nasty corrosion of the said parts and significant reduction of the motor’s lifespan. Another prevalent issue is clogged fuel systems, besides gasoline turning into varnish.

Does Ethanol Fuel Treatment Work

Yes, and the products listed here stand out in doing just that. Most are able to achieve this effect by either absorbing the water or inducing it to be burned off before phase separation can occur. In the end, as long as these products prevent phase separation, ethanol damage doesn’t start.

Does Sea Foam Stabilize Ethanol Fuel

It will always provide a certain degree of protection against ethanol, but I can’t say that this applies to all types and ages of engines. In other words, don’t expect Sea Foam to be a cure-all for ethanol issues.

With that said, is Sea Foam a good fuel stabilizer? Overall, it is, especially if you want to remedy ethanol problems. However, it wouldn’t be as satisfactory in keeping your fuel viable for a long time.


Do you now have a clear image of the best ethanol fuel treatment? Based on my experience, it’s any product that keeps engines running as they should. In short, it should work. I can back the numerous claims of other satisfied users, having done some trial-and-error myself. I hope that with this guide, you won’t have to take too much time and effort to discover what works for you.

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