If you’ve ever walked the cherished halls of your local auto parts store, you’ve probably come across an aisle stuffed to the brim with different juices, elixirs, sprays, and additives. Many of those bottles and cans are pretty useful (I swear by Liquid Wrench), while others offer pie-in-the-sky cures for stuff like leaking radiators (if you can’t seal it from the outside, just give up and replace it).
Fuel stabilizers usually occupy a shelf in that aisle. As the name suggests, these liquids, when added to a tank of gasoline, promise to “stabilize” the fuel’s chemical properties so it lasts longer (gasoline lasts up to six months before degrading, according to Exxon Mobil). Some fuel stabilizers promise to stretch that period to up to two years.
These stabilizers don’t just promise to keep fuel healthy. They also promise to keep old fuel from destroying your car. Road & Track has a neat little explainer on how that happens:
What is this magic tonic stabilizing? It’s trying to prevent oxidation. Gasoline can form gummy deposits and layers of varnish that gunk up any part of the fuel system they can reach. Most gas contains some amount of ethanol, and that spells more trouble; ethanol is hygroscopic, meaning it attracts water from the atmosphere. Water and ethanol are corrosive, which is bad news for older tanks, fuel lines, and carburetors. Ethanol can also do nasty things to rubber seals.
What Exactly Is Fuel Stabilizer?
According to Berryman, a manufacturer of fuel additives and treatments, stabilizers work by employing a mixture of antioxidants and lubricants that, on a chemical level, repel water and limit evaporation. Basically, it’s trying to stop water from building up in your gas and wrecking your car’s fuel system from the inside. But does it actually work? One man decided to spend five years running a series of experiments to find out.
Todd Osgood of the Project Farm YouTube channel has been performing at-home comparison experiments on a litany of different products for years, from tire pressure gauges to ratcheting wrenches to anti-freezing diesel additives. In a world where it feels like companies are increasingly trying to deliver less performance for more money, Osgood’s independent backyard shed tests are a refreshing sight, even if not all of them are that scientifically precise (though he does a pretty good job in general).
Though Osgood doesn’t wear a lab coat, he likes to be incredibly thorough with his tests. For this experiment, he wanted to compare four of the most popular products often used as stabilizers: STA-BIL, Yamalube, Star Tron, and K100.
“This review has taken a total of about five years to complete, a very long review,” Osgood says to start off. “However, I think it’ll be worth your time. The first three years of the review, I tested some fuel, and after the first three years, I decided to create a new batch of fuel, and that took an additional two years.”
The Corrosion Test Has One Big Standout
He threw in Marvel Mystery Oil and SeaFoam into the mix for their similar treatment properties, and also some two-stroke oil, just to see what would happen. His first test involved jarring up six pieces of pot metal (cheap metal made of stuff like aluminum, lead, and zinc) and mixing them with some fuel mixed with 10% ethanol, the additive, and a tiny bit of water.
Osgood then left the jars alone for three whole years to see if any of the stabilizers would prevent corrosion. Amazingly, out of the six treatments tested, he found that only one, STA-BIL, was able to keep the metal fully clean. Every other product let corrosion build up on the metal to some degree (though K100 came in a close second, with just a few bits of corrosion on the metal).
The Rubber Hardening Test Was A Bit Less Conclusive
For the next test, Osgood jarred six pieces of rubber hose paired with some fuel and each additive to see how well the products could help with hardening of the rubber (the goal here is to keep the rubber as soft as possible, so it doesn’t harden and crack, causing a leak). To test the rubber’s hardness, he used a handheld durometer, which uses a spring-loaded pin to measure how much force is necessary to penetrate a surface. No matter the brand, there wasn’t much of an impact on hardness, but interestingly, it was the STA-BIL that showed a slight edge here, too.
Like A Hydrocarbon To A Flame
After that, Osgood tried to see which of the stabilized fuel mixtures would ignite using a simple lighter after sitting for 20 months. Amazingly, the STA-BIL was, again, the only product to show signs of life here. It was the sole mixture to actually ignite when presented with a flame (even if it was just for a second). None of the other mixtures could muster that performance.
The Experiment You Should Actually Care About
For the final and most important test, Osgood wanted to see how the old fuel and stabilizer would run when put through a generator. The fuel mixed with the SeaFoam, the Marvel Mystery Oil, the K100, and the Yamalube all needed starting fluid for the engine to fire up, while the Star Tron and the STA-BIL didn’t need assistance. Of the six, Osgood praised the Star Tron and the STA-BIL for keeping their respective spark plugs clean (he swapped out the generator’s spark plug for each test run to ensure the competitors would have equal chances of running).
Like I mentioned before, these sorts of tests aren’t perfectly scientifically precise, being done with mason jars in a barn by a (smart) YouTuber and all. So it’s best to keep that in mind. All that being said, it seems like there are a few brands that are better than others, and one clear winner. We don’t want to spoil Osgood’s five years of hard work, so we’ll leave it to you to watch the full video to find out where each brand ended up.
Top graphic image: Project Farm/YouTube
Saw the video yesterday and it was an interesting watch with a bonus 1 year update on headlight restoration. I’ve been using Stabil for winter storage since that’s what’s usually available at the auto parts stores here and it works well (although winter storage for me is only ~4 months) 🙂
I’ve started using the $20 a can premium small engine fuel in my Gravely two wheel tractor because the carburetor is super sensitive to ethanol. Even buying supposedly ethanol-free recreational fuel left it running rough. It’s worth paying extra to keep the old beast running well. Beyond that I’ve used pump gas with stabilizer in my other yard equipment without any major problems.
Out of curiosity, did you store your ethanol-free fuel in a plastic can or a metal one? There’s a decent chance the moisture introduction and loss of volatiles in a typical plastic can accounts for the difference you’re seeing.
The Gravely is used sparingly so the gas stays inside its steel fuel tank. Ultimately I don’t trust that any gas purchased from a pump station is truly ethanol-free. Sta-Bil and Star Bright have been enough to make pump gas ok for all of my small engines except for the one in the Gravely. It’s a 40+ year old machine and the Zenith carburetors are known for having very little tolerance for ethanol.
I forgot the best thing you can do for a small engine prior to storage- Close the fuel valve and let it use up whatever is still in the line and carburetor. I do that with the snowblower and generator every time and have never had issues getting them to start later.
I think the fuel in the tank is ethanol free, but there’s leftover fuel in the filler hose from whoever last used the gas pump. When I fill gas cans with ethanol free fuel, I top the car off first to flush out whatever is in the gas pump’s filler hose.
Not something I’d considered because all my local ethanol-free options use dedicated hoses and nozzles. Definitely a valid concern if that isn’t the case.
Your seasonal shutdown is the same as I’ve done for years with similar results. I used to use the wall-powered electric start on the first start for the snowblower, but it just always started on the first or second pull so I don’t bother anymore. Same for the mower.
I tend to watch his videos on 2X speed. I try not to watch too many as just one will make the algorithm suggest tool reviews for weeks.
I do use nothing but non oxy and stabill in all my small engines and the fuel can sit over the winter just fine.
Touch wood, I’ve had good luck with my motorcycles, and lawnmower etc stored with ethanol free gas and Sta-Bil for up to a year and I’d guess the routine started over 10 years ago.
My Honda carbed motorcycle is only just getting rid of it’s tank of treated fuel as it doesn’t see much use and now it is almost repeat time.
An important rule is to make sure your gas tanks are full so that there is little volume susceptible to condensation or tank area to rust/corrode.
Ethanol gas is evil, thanks politicians for stupid legislation.
A shout out to Project Farm one of the few trustworthy YouTube testing sites.
The best kind of product Influencer.
All my small engine gas is alcohol free, I put in Stabil right away, not just for storage. Never have any issues. We have about two dozen various small engines
Thanks for spoiling the conclusion, I’m having a hard time enduring his videos.
My workshop is pretty dry, so I’ve had 10+ year old gasoline burn just fine. But I’ve also had nasty rust porridge in the bottom of a tank, which was no fun at all, so I will consider some Sta-Bil.
I got about 30 seconds into the video and had to turn it off. His voice is… unpleasant.
My YT algo constantly suggests his comparison videos. I find the topics generally interesting so I click. But after 2-3 mins, the overly rapid high pitched delivery and the audio editing where he removes dead air between his sentences, it’s tiring for my ears so I click away.
Relax the vocal chords and slow down the delivery just a little bit, and his viewership would go up (at least by one). 😉
This was your once chance to just that “some geniuses” headline and it actually be true.
To be fair to the author I think they stopped using that before he was hired.
Yeah, his presentation style (the yelling) can be a bit stressful and annoying, but the amount of testing he does is terrific. I have bought several things based on his recommendations over the years, and have yet to be steered wrong.
you get stressed out watching his videos? How do you make it through a day out in public, he is much less stressful than just a visit to the local walmart.
Well, I don’t generally get yelled at in the local walmart. 🙂
ha! that made me laugh. Your walmart sounds nicer than mine!
The Car Care Nut. AMD is a certified Toyota master tech who has his own shop. If I still lived in Chicago, I’d take my car there.
His presentation voice is like nails on a blackboard, but his tests are pretty well-structured and very thorough. Especially after the first few, because he took a lot of good advice on how to design them better. The content’s good enough to make it worth the presentation, but I definitely skip around to the graphs and charts sometimes instead of watching the whole thing.
Yeah, same. But the content is great.
To echo the words of others, Project Farm is my first search when I’m looking at a new product. His commitment to impartiality speaks to me and he really separates the wheat from the chaff.
As a scientist, I deeply respect what Project Farm accomplishes and their dedication to well-designed tests. Plus, Todd is living proof that substance beats form any day, at least for the 3.65 million thinking individuals who’ve subscribed to his channel. His voice and mannerisms are annoying (at least to me) and he has little in the way of style, but you can’t say anything against his results and informative data. He’s the anti-Kardashian.
I am in northern Europe, so your mileage will vary, regarding fuel quality:
First, the fuel here does not turn nikasil liners into sandpaper (BMW, Honda), and oil change intervals are nominally 10-15kkm for MCs and 15-25kkm for cars, without trouble.
Second, in my region with warming winters and practically no carburettors, I am not sure we get summer/winter fuel blends anymore.
How do I deal with off season:
For carbed MC: Last couple of tanks run zero ethanol fuel. Last run, when home hot, disconnect tank (including vacuum cock), run engine adding oil (whatever is in oilcan) to fuel line. When engine starts to die, activate cold start carburettor (sometimes labelled choke, on non RR vehicles) until engine dies. Now carbs are filled with a heavy oil petrol mix, that will not stick even if fuel is oxidised. On next startup, maybe drain bowls.
For FI MC: Last couple of tanks run zero/low ethanol fuel. (Last I looked, Shell VPower was an option, but check.)
Garden stuff, mover, generator, hedgetrimmer … Keep tank full, and if possible, drain bowl and dump into tank, for easy start in new year.
Oh, and currently I am using 20+ year old petrol in the garden stuff; it has been stored in metal jerries since a threat of a general strike.
Project Farm is the only reputable review channel on YT.
Name another channel that puts in as much work and tests as many products as PF. And he’s not sponsored and pays for the products himself. So called reputable review magazines like Consumer Reports don’t do nearly as much work and I don’t think they’ve ever done a multi-year review like this one.
Torque Test Channel is another guy I trust.
Good call! I’m glad to see that they are expanding into more products than just drills, hammer drills, impacts and the like. There’s only so many of those tests one channel can do. Hope they really start doing a whole variety of tools and other products.
Best channel on YouTube!
I’m impressed with Lake Speed Jr.
Huh. I never liked his old man because after his first (and only) win in NASCAR he balled like a baby on TV talking about God and Jesus and the like. Like, not just a ‘I wanna praise god for my win’ but blubbered like a heartbroken high school girl. I was only 8 years old but even I was like …. Bruh, this is over the top. Granted, I never met the guy, so I have no idea how he really is. I’ve met a bunch of NASCAR dudes from the 80’s and 90’s and most of them were a-holes, so I guess that colors my opinion, too. The nicest two were Dick Trickle and Bobby Labonte, though.
Jr. seems like a cool dude, though.
I’ll have to look them up. Never heard of them.
Over the course of a normal winter of sitting let’s say 5-6 months I’ve used Seafoam and never had an issue in both gas and diesel engines.
i also don’t use ethanol fuel in anything other then the vehicles that get driven frequently so there is that.
I am certainly going to try some Stabil now in one of our gas powered Farmall tractors just to see if over the six months it sits if it starts any different.
i really like the Project Farm tests and as far as I’m concerned it’s the only real world test out there.
i trust him and what he says.
I prefer to say these are real world tests. Far more valuable than scientific tests that don’t do real world results.
Consumer Reports might be OK but if Project Farm says something works I believe it. I’ve bought so many items based on his reviews and I’ve never been disappointed.
Consumer Reports is … fine, but so many of their review units are sent to them by the manufacturer. You never know if you’re reading about a cherry picked unit that got ‘blueprinted’ before it was sent. Todd buys his stuff out of pocket retail, so it’s more indicative of a likely scenario.
I was pretty sure Consumer Reports buys all their items at retail to avoid that issue.
You are correct according to their website. Thanks!
Consumer Reports seemed to be better a decade ago. I’m not sure what happened. New editors? New owners?
Their in-depth testing is now boiled down to quick rankings in most of my recent experience. Like most recent science, their Methods are no longer a priority when writing their articles. Such a shame.
That, and companies seem to cycle price and quality, so the recommendation for this year might sell a lot based on current price and past quality, but it will crap out in 2-3 years. Models don’t exist long-enough for Consumer Reports quality results to come back.
Never had it sit that long (usually 6 months or so) but Sta-Bil always worked great in my generator.
Works great on my yard equipment snowblower and garden tractor always start after the off season
2+ year old gas in the mower and generator.
Using Sta-Bil.
Both crank right up without an issue.
I love his YouTube channel and have made several purchases purely based on his testing.
I’ve been using Sta-bil for decades for my yard equipment gas tank since I use so little at a time. I also buy the pricey ethanol-free premium fuel to help prevent that corrosion that ethanol brings. So far, I’ve never had to rebuild a carb, so it must be doing something.
Looking forward to ditching gasoline small engines entirely, but the Mantis rototiller my grandpa gave me has sentimental value and really punches above its weight class for my modest garden.
Same here – I probably refill my 2 gallon can twice a year and Sta-Bil hasn’t let me down yet. I’m even cheap enough to use regular gas in the mower rather than ethanol-free
I love Project Farm!
He really tries to do a real world approach to things, while trying to keep things relatively scientific/accurate. He did one on rechargeable AA batteries (because we use a lot of them for random shit around the house) and his tests showed that actually IKEA has some of the best ones.
Sure as shit, we bought the IKEA ones and they lasted much longer vs. every other one we were using. But you gotta buy the higher capacity ones.
If you love Todd, also watch The Torque Test Channel. Similar tests for everyday items (tools, flashlights ,etc.), although a bit more scientific.
I will gonna test that!
Huh, I always just used Sta-Bil because it was easiest to find. Good to know it’s the best
Paul Harvey used to shill Sta-Bil.
I’m sure it is a much better product than the “magic music box” Bose Wave radio with speakers behind directional tunnels that he would push like a carnival huckster. The newest, latest, most improved version gets just 3.5 stars out of five on Cnet.
Those Bose wave stereos are good, but they were wildly expensive for what you got.
I picked up a cheap one, second hand, and I’m happy with it, but I wouldn’t have been as happy if I’d paid full price (about 5-6 times more than I paid)
I think that’s the biggest problem with Bose stuff. Not that it’s *bad* but that it costs too much. For what you’re spending on it, you could get better stuff.
But there’s such a big diminishing returns curve in audio equipment that once you get above a certain threshold, ‘better’ is often imperceptible to 90% of consumers. They can tell you a $100 speaker sounds WAY better than a $10 speaker, but probably couldn’t pick out the $2000 speaker from the $300 one. Especially since a lot of times ‘better’ is subjective. Too many different sound signatures and emphasis on different things so that speakers sound… different from each other, but which one is ‘better’ is often in the ear of the beholder. Like saying ‘What’s the better car? A base model Hyndai Accent, a 540i, Mustang or a Cayman RS?’
Well, almost no one is going to say the Accent, but the Mustang is the ‘fastest’, the 540i rides the nicest and is most comfortable and the Porsche probably handles the best.
Take the same test method Project Farm uses — question, research, hypothesis, experiment, analyze, and communicate — and move it from a bucolic setting to a sterile lab environment and I don’t think the results would be different.
Project Farm is sort of a spiritual successor to Mythbusters mixed with Consumer Reports.
Yeah, his apparatus might not always be lab-grade, but his tests are well-reasoned and he puts thought into maintaining consistent test conditions across each candidate product (using weights applied to chainsaws for cut speed tests versus using his arm, etc). He also openly states more subjective test results, and always pays full price for every product himself (no freebie test units that may sway his opinion or be “stacked” with extra manufacturer care over off-the-shelf consumer units).
He has gone back and revised some tests after commenter feedback too, so there’s a decent feedback loop.
Sta-Bil Marine 360 is good stuff. It’s kept my small engines generally problem free in extended storage.
Project Farm is great. He’s very thorough, although his rapid fire presentation takes some getting used to.
I think that’s mostly caused by editing out all of the running time without dialog including even gaps between sentences.
I can’t be the only one who immediately thought of this experiment?
Ha, just a few years before he took on the Paperboy 2000:
https://www.theautopian.com/this-was-one-of-the-strangest-sitcom-cameos-of-a-post-apocalyptic-movie-car-cold-start/
As someone who goes through almost a whole bottle of Stabil every fall/winter, these results make me happy.
I only go through about half a bottle but same.
What do you put in the remaining Sta-bil to ensure it doesn’t go bad?
Gas
Whiskey and a slice of orange
You I like 🙂
More Sta-bil
Same. I’ve used Stabil every fall (and spring when I owned a gas snowblower) for decades and am glad to know that the experiment results match my anecdotal experiences.