The best fuel stabilizer for most small engines is STA-BIL Storage. In Project Farm's five-year test it was the only treatment that kept a piece of carburetor-type pot metal free of corrosion over three years in water-contaminated E10, and in a second, 20-month batch a STA-BIL sample was the only one that began to light. Bob Vila and The Drive name STA-BIL Storage too. Add 1 ounce to every 2.5 gallons of fresh gas and run the engine for 5 minutes. For a string trimmer, blower or chainsaw, STIHL's storage advice points to ethanol-free canned premix such as STIHL MotoMix. For a diesel tractor or generator, STA-BIL Diesel.
What it is: fuel stabilizer, also sold as gas stabilizer, is an additive you pour into fresh gas so it breaks down more slowly while an engine sits; STA-BIL describes its formula as antioxidants, anti-corrosives and detergents. One thing no bottle does: bring old gas back. Honda says fuel stabilizers will not reconstitute stale fuel, and STA-BIL says its own product will not restore old gasoline. Stabilizer goes into fresh gas, before the engine is put away.
Disclosure: we earn from qualifying purchases as an Amazon Associate, which never changes what we pick or what you pay. We checked every product's availability on Amazon on September 28, 2026; stock can change. Prices move, so we leave them off: each "Check price" link shows the current one.
Jump to: The picks | How much to add | Engine by engine | What it is and does it work? | Mowers and snow blowers | Generators | 2-stroke tools | Old gas
Best fuel stabilizers at a glance
| Product | Buy it for | Dose on the label | How long, per the maker | Backed by | Link |
|---|---|---|---|---|---|
 1. STA-BIL Storage Fuel Stabilizer
|
Best overall: a mower, snow blower or generator going into storage | 1 oz per 2.5 gallons | Up to 24 months (its FAQ warns ignitability fades after 12) | Project Farm (tested five years); FortNine; Bob Vila; The Drive | amazon |
 2. Star Tron Enzyme Fuel Treatment, Concentrated Formula |
Treating a lot of gas across many engines | 1 oz per 16 gallons (1 oz per 8 on the first dose) | Up to 2 years | Bob Vila; The Drive (formula unclear); Project Farm tested a sibling formula | amazon |
 3. VP Racing SEF 4-Cycle Small Engine Fuel |
A 4-stroke engine you start a few times a year | None: pour it in as fuel | 2 years in the tank, 5 years sealed | No tester; FortNine's advice to use ethanol-free gas | amazon |
 4. STIHL MotoMix 50:1 Premixed Fuel |
Trimmers, blowers and chainsaws that take 50:1 | None: already mixed | Up to 2 years | No tester; STIHL's own storage advice | amazon |
 5. STA-BIL Diesel Fuel Stabilizer |
Diesel tractors, generators and cans | 1 oz per 5 gallons for storage | Not stated | Bob Vila | amazon |
 6. STA-BIL 360 Protection Ethanol Fuel Treatment |
Treating every gas can you fill | 1 oz per 5 gallons | Up to 12 months | Bob Vila (the 4-ounce size) | amazon |
How we chose
We did not test these ourselves. We read the three tests we could find that measured how treated fuel holds up. Project Farm bought its products and ran a test five years end to end: one batch of E10 sat three years in jars with pot metal, rubber hose and a little water, and a second batch sat 20 months and was run through a fuel-injected generator. Oak Ridge National Laboratory aged pump E10 with three stabilizers in sealed cans for up to 12 months and had it lab-tested. FortNine measured evaporation, water uptake, freezing and oxidation in short bench tests. We added the two researched roundups, Bob Vila and The Drive, and set every pick's Amazon listing against its maker's page or FAQ and the storage advice from Honda, Briggs and Stratton, Toro and STIHL.
The rules: in stock on Amazon on September 28, 2026, and each pick does a different job. Two notes. The Star Tron Project Farm bought is the Small Engine Formula, which was out of stock on September 28, so pick 2 is the Concentrated Formula Bob Vila names, a sibling that test did not run. The Drive's best overall is Star Tron's enzyme treatment, which its specs describe as the 1-ounce-per-16-gallons concentrate while its link goes to the Small Engine Formula. And no tester has tried picks 3 and 4: they are here because FortNine's own conclusion is to use ethanol-free gas if you can get it, and STIHL's advice for 2-stroke tools points the same way.
The best fuel stabilizers, by job
1. STA-BIL Storage Fuel Stabilizer: best overall
Check price. STA-BIL's red bottle, in the 8-ounce size, which treats 20 gallons at the label dose; STA-BIL says an opened bottle lasts 2 years, so buy the size you will use in that time. For a generator, several machines and a row of cans, the 32-ounce bottle treats 80. The directions are simple: 1 ounce for every 2.5 gallons of gas, then run the engine for 5 minutes so treated fuel reaches the whole system. STA-BIL rates it for keeping fuel fresh for up to 24 months, for ethanol blends up to E85 and for 2-cycle and 4-cycle engines, and says it contains no alcohol. Project Farm's and FortNine's product links both go to this Storage formula, in the 32-ounce size Bob Vila picked as best overall.
Project Farm's jars are the reason it leads. After three years in water-contaminated E10, the pot metal in the STA-BIL jar showed no corrosion at all, and Project Farm gave it the best possible rating; the metal in the Star Tron, Sea Foam and untreated jars corroded badly. STA-BIL's jar also kept the rubber fuel hose softest of the group. After a second batch sat for 20 months, the STA-BIL sample was the only treated fuel that began to ignite, and in the generator it started in about 2.5 seconds without starting fluid and left a spark plug that looked almost new. One caution covers that whole 20-month batch: Project Farm's video links this Storage formula, but its transcript calls the 20-month STA-BIL fuel "Stable 360", so those results may belong to STA-BIL's 360 formula (pick 6). FortNine's test found STA-BIL the only additive that noticeably held down water uptake, and rated its protection against oxidation passable. The Drive recommends it too, and Bob Vila makes it its best overall.
Where it loses: it does not keep gas fresh forever. Project Farm's three-year STA-BIL fuel was not flammable at all, and its 20-month fuel was stale, just less stale than the rest; Hagerty, reporting the test, notes the win rested mostly on corrosion rather than on how burnable the fuel stayed. STA-BIL's own FAQ says gas stored more than 12 months tends to lose ignitability (another answer on the same page says 24) and that no additive prevents it. FortNine found every stabilizer let a little more fuel evaporate than untreated gas. It also takes more ounces per gallon than picks 2, 5 and 6.
2. Star Tron Enzyme Fuel Treatment, Concentrated Formula: best concentrate
Check price. An 8-ounce bottle that treats 128 gallons, and the listing says it works in all engines and all fuels. Star brite's how-to page gives 1 ounce for every 8 gallons on the first dose, then 1 ounce for every 16 gallons at each refill, added just before you fill up, and says overdosing is not harmful. Star brite's listing for the 32-ounce size of the same concentrate says it stabilizes fuel for up to 2 years and helps prevent phase separation by dispersing water as submicron droplets that are safely eliminated while the engine operates.
For one mower going away for winter, buy pick 1. Buy this for gallons per bottle across a mower, a generator and a couple of gas cans, because a little goes a long way. Bob Vila picks the concentrate, noting that one bottle goes far, and The Drive makes Star Tron's enzyme treatment its best overall, though its link goes to the Small Engine Formula. In Project Farm's generator run the Star Tron fuel fired in 2.5 seconds without starting fluid and left a clean plug, tying STA-BIL for the best score.
Where it loses: the two tests that report Star Tron results by name were not kind to it. In Project Farm's three-year jar the Star Tron did not stop corrosion and the metal showed pitting, and although Star Tron says it can rejuvenate old fuel, its 20-month sample would not light. FortNine found StarTron drew in more moisture than untreated fuel and scored it badly on oxidation. Project Farm used the Small Engine Formula, and FortNine does not say which formula it used. Oak Ridge included a Star Tron enzyme treatment but did not say which sample was which. The Drive also finds the bottle awkward to pour and measure.
3. VP Racing SEF 4-Cycle Small Engine Fuel: best for engines you rarely start
Check price. Not an additive but the fuel itself: three quarts of 94-octane, ethanol-free gas for 4-stroke engines, with no oil in it. The listing says it stays stable for 2 years in the tank or 5 years sealed in the can, and VP's product page says the same.
Buy it for the engine you start a handful of times a year: the backup generator, the tiller, the snow blower in a mild winter, the pressure washer. FortNine ended its test by telling viewers to fill with ethanol-free gas for storage if they can get it, and Honda, Briggs and Stratton and STIHL all warn about ethanol in small engines. Canned ethanol-free fuel avoids that problem and needs no dosing.
Where it loses: no tester has put it through a storage test, so the 2-year and 5-year figures are VP's. It comes by the quart, which suits a tiller or a small generator more than a riding mower you fill every weekend.
4. STIHL MotoMix 50:1 Premixed Fuel: best for 2-stroke tools
Check price. One quart of ethanol-free fuel already mixed 50:1 with STIHL HP Ultra oil, for any 2-cycle engine that calls for 50:1. The listing says it stays fresh for up to 2 years.
This is the pick because of what STIHL says about home-mixed fuel. STIHL recommends not storing or using fuel mix older than 60 days, preferably no older than 30, even with a stabilizer, and storing its tools dry over winter: empty the tank and let the engine idle until it stops. The exception is MotoMix, which STIHL says contains no ethanol, has a storage life of up to two years and can be left in the machine during seasonal storage. If you run a string trimmer, leaf blower or chainsaw a few times a season, a can on the shelf beats a jug of mix going stale.
Where it loses: it is 50:1 only, so check your tool's manual; TruFuel sells a 40:1 mix for brands that need one. No tester has run it. And one quart does not go far on a big saw, so heavy users may still mix their own and follow STIHL's 30 to 60 day rule.
5. STA-BIL Diesel Fuel Stabilizer: best for diesel
Check price. STA-BIL's diesel formula, 32 ounces. For storage, STA-BIL says 1 ounce to 5 gallons; for use at every fill-up, 1 ounce to 10 gallons, and not to overtreat. The listing says it prevents sludge and sediment, removes water, and works with all ultra-low sulfur diesel and biodiesel blends.
Use it in a diesel compact tractor, a diesel generator or the diesel cans that feed them. Do not use the red gasoline bottle instead: STA-BIL says regular STA-BIL in diesel will not harm the system but will not be effective, and that its red dye can cause legal issues in on-road diesel, since off-road diesel is dyed red for tax purposes. Bob Vila names this formula its best for diesel engines.
Where it loses: it is for diesel only, and Bob Vila warns against putting it in a gasoline system. No tester has aged diesel with it, and STA-BIL does not put a month figure on the storage dose.
6. STA-BIL 360 Protection Ethanol Fuel Treatment: best for treating every gas can
Check price. A 12-ounce bottle of STA-BIL's ethanol treatment. STA-BIL rates it for storage and everyday ethanol treatment at 1 ounce to 5 gallons, half the dose of pick 1, and the listing says to use it at every fill-up and that it stabilizes fuel for up to 12 months.
The case for it comes from Honda: since you never know how long gas will sit in a portable can, Honda recommends adding stabilizer every time you fill one with fresh fuel. For cans you refill all season and empty within the year, each ounce of this treats twice as much gas as an ounce of pick 1. Bob Vila picks a 4-ounce bottle of this formula as its best for gas jugs.
Where it loses: its storage claim is half of pick 1's, so for a machine going away until next year, use pick 1. Bob Vila also argues that a stabilizer is not necessary for gas you will burn within a month or two; Honda's advice is the reason to do it anyway for cans. Oak Ridge included this formula in its 12-month study but did not publish which sample was which, and it found untreated gas in sealed cans stayed within specification for the year. Project Farm's transcript names "Stable 360" in its 20-month run, but its product link is the Storage formula, so we credit that test to pick 1.
Also considered: products that missed the list and why
Sea Foam Motor Treatment (not linked, because we advise against it for storage). The listing says it keeps gas fresh for up to 2 years, and TruePrepper calls it its versatile pick. Its listing leads with fuel system cleaning. As a storage stabilizer it did poorly in both tests: in Project Farm's three-year jar it did not stop heavy corrosion, its 20-month fuel would not light, and the generator needed 21 shots of starting fluid to run on it. FortNine rated its oxidation result the worst of the group, and even The Drive, which lists it, says it is not good for long-term storage.
Lucas Oil Fuel Stabilizer. Bob Vila's runner-up and an honorable mention at The Drive, both for the quart size; the quart was out of stock on September 28, so we link the 15-ounce bottle. Lucas says 1 ounce treats 2.5 gallons, the same dose as pick 1, that it contains no alcohol and that it is safe in 2-cycle and 4-cycle engines. It missed because none of the tests we read aged fuel with it (Oak Ridge's Lucas sample was a different product, its Safeguard conditioner), while pick 1 has five years of results. Bob Vila and The Drive quote a heavier 1 ounce per gallon for the quart; Lucas's own page says 2.5 gallons.
K100 Gasoline Fuel Treatment. The strongest runner-up in the tests: second to STA-BIL on corrosion in Project Farm's jars and third in its generator run, and the only additive FortNine found kept oxidation fully at bay. K100's storage directions are to double the normal dose. It missed on the cold: FortNine's water-laden K100 sample froze solid, and FortNine says that makes it not the best choice for cold storage. Project Farm also notes it contains alcohol-based ingredients.
Yamalube Fuel Stabilizer and Conditioner Plus. Bob Vila's pick for yard equipment, at 1 ounce per 3 gallons in season; the directions a Yamaha parts dealer lists raise that to 1 ounce per gallon for storage over 2 months. Project Farm tested this Plus formula: its metal corroded, though less than untreated fuel, its 20-month fuel was stale, and the generator needed starting fluid to fire. Pick 1 did better on each of those.
Honda Fuel Stabilizer, part 08732-0800 (not linked). The 8-ounce bottle Honda shows on its fuel page for EU generators, so a natural choice if you own one; a Honda dealer can match the part number. We do not link it because the Amazon listing we found is muddled: it says 1 ounce to 5 gallons, which is 40 gallons a bottle, but also that the bottle treats up to 80 gallons, and it is sold under a generic brand name. No tester has tried it.
STA-BIL 360 Marine. The blue bottle, Bob Vila's pick for small boat engines, at 1 ounce to 10 gallons. It missed on its own listing, which calls it an in-season treatment and says to use STA-BIL Storage, pick 1, for storage.
TruFuel 4-Cycle and TruFuel 50:1. Canned, ethanol-free fuel in both types. TruFuel says it stays good for at least 2 years after opening and more than 5 years unopened, and it sells a 40:1 mix too. It does the same jobs as picks 3 and 4. We put VP and STIHL ahead because their listings are clear. We link only the 50:1 can: the TruFuel 4-Cycle listing we found says it is for engines "requiring a 50:1 mix", which does not describe a 4-stroke fuel.
PRI-G (not linked). TruePrepper's best overall, at 1 ounce per 16 gallons. Its Amazon listing, the 16-ounce bottle, was out of stock when we checked on September 28, 2026, and none of the tests we read aged fuel with it, so it is not on the list.
How much fuel stabilizer per gallon: the dose for your can
Labels give a ratio; you have a 1-gallon can or a 5-gallon jug. This table does the arithmetic from each maker's storage dose, the heavier rate where a maker gives two. Small doses are in teaspoons and tablespoons using NIST's kitchen equivalents (1 fluid ounce is 30 mL, a teaspoon 5 mL and a tablespoon half an ounce), so a measuring spoon you keep for the garage will do. Canned fuels (picks 3 and 4, TruFuel) need no dose.
| Product | Storage dose | 1 gallon | 2 gallons | 2.5 gallons | 5 gallons | One bottle treats (computed) |
|---|---|---|---|---|---|---|
| 1. STA-BIL Storage | 1 oz per 2.5 gal | 0.4 oz (about 2 1/2 tsp) | 0.8 oz (about 5 tsp) | 1 oz (2 tbsp) | 2 oz (4 tbsp) | 20 gal (8 oz); 80 gal (32 oz) |
| 2. Star Tron Concentrated, first dose | 1 oz per 8 gal | 0.125 oz (3/4 tsp) | 0.25 oz (1 1/2 tsp) | 0.31 oz (about 2 tsp) | 0.63 oz (about 3 3/4 tsp) | 64 gal (8 oz) |
| 2. Star Tron Concentrated, refills | 1 oz per 16 gal | 0.06 oz (about 3/8 tsp) | 0.125 oz (3/4 tsp) | 0.16 oz (about 1 tsp) | 0.31 oz (about 2 tsp) | 128 gal (8 oz) |
| 5. STA-BIL Diesel, storage | 1 oz per 5 gal | 0.2 oz (about 1 1/4 tsp) | 0.4 oz (about 2 1/2 tsp) | 0.5 oz (1 tbsp) | 1 oz (2 tbsp) | 160 gal (32 oz) |
| 6. STA-BIL 360 Protection | 1 oz per 5 gal | 0.2 oz (about 1 1/4 tsp) | 0.4 oz (about 2 1/2 tsp) | 0.5 oz (1 tbsp) | 1 oz (2 tbsp) | 60 gal (12 oz) |
| Lucas Fuel Stabilizer | 1 oz per 2.5 gal | 0.4 oz (about 2 1/2 tsp) | 0.8 oz (about 5 tsp) | 1 oz (2 tbsp) | 2 oz (4 tbsp) | 37.5 gal (15 oz) |
| K100 Gasoline Treatment | Double the normal dose: 1 oz per gal | 1 oz (2 tbsp) | 2 oz (4 tbsp) | 2.5 oz (5 tbsp) | 5 oz (10 tbsp) | 8 gal (8 oz) |
| Yamalube Stabilizer and Conditioner Plus | 1 oz per gal (storage over 2 months) | 1 oz (2 tbsp) | 2 oz (4 tbsp) | 2.5 oz (5 tbsp) | 5 oz (10 tbsp) | 32 gal (32 oz) |
| STA-BIL 360 Marine | 1 oz per 10 gal | 0.1 oz (about 1/2 tsp) | 0.2 oz (about 1 1/4 tsp) | 0.25 oz (1 1/2 tsp) | 0.5 oz (1 tbsp) | 320 gal (32 oz) |
| Sea Foam Motor Treatment | 1 oz per gallon | 1 oz (2 tbsp) | 2 oz (4 tbsp) | 2.5 oz (5 tbsp) | 5 oz (10 tbsp) | 16 gal (16 oz can) |
What the table shows: doses differ sixteenfold, from 1 ounce per gallon (Sea Foam, and K100 and Yamalube at their storage rates) to the Star Tron concentrate's 1 ounce per 16 gallons at refills. The Star Tron concentrate treats 128 gallons from 8 ounces at the refill rate, while the 32-ounce STA-BIL Storage treats 80. At one ounce per gallon, a full can of Sea Foam doses just 16 gallons and a bottle of K100 just 8. And for the 1-gallon can by the mower, pick 1 needs about 2 1/2 teaspoons. Can you overdo it? STA-BIL says over-dosing is fine up to 4 times its rate, Star brite says overdosing Star Tron is not harmful, and STA-BIL says not to overtreat its diesel formula. The Honda bottle is left out because its listing gives two rates that do not agree.
Best fuel stabilizer for small engines, engine by engine: what the makers say
| Your engine or fuel | What the maker says | What to buy here |
|---|---|---|
| Walk-behind or riding mower, snow blower (4-stroke) | Briggs and Stratton: store it filled with treated fuel and run the engine a few minutes. Toro: 1 ounce of fuel stabilizer per 2 gallons, and a partly full tank is fine. | Pick 1, or pick 3 if it is started only a few times a year |
| Honda EU inverter generator, 1 to 2 months | Fill with fresh fuel plus stabilizer, run it outdoors 10 minutes | Pick 1 |
| Honda EU inverter generator, 2 to 12 months or run less than monthly | Drain the carburetor | Pick 1 in the tank and cans, plus the drain |
| Honda generator or engine stored more than a year | Drain the fuel tank and carburetor; even treated gasoline can deteriorate | Drain it; refill with pick 3 or freshly treated gas when you need it |
| STIHL trimmer, blower or chainsaw (2-stroke) | Pump-gas mix no older than 60 days, even with stabilizer; store dry, or leave MotoMix in it | Pick 4 |
| Diesel tractor or generator | STA-BIL: use the diesel formula; regular STA-BIL will not be effective | Pick 5 |
| Gas cans | Honda: add stabilizer every time you fill a can | Pick 6, or pick 1 for a can that may sit past 12 months |
| Gas that is already stale | Honda and STA-BIL: stabilizer will not restore it | Nothing on this page; see old gas |
The makers do not agree on everything. Briggs and Stratton and Honda say to store the tank full, and STA-BIL says 95 percent full, to keep air and moisture out, while Toro says a lower level is fine in its equipment. STIHL prefers its 2-stroke tools stored empty, and Honda prefers draining for storage beyond about a year. Follow the manual for your machine.
What is fuel stabilizer, what does it do, and does it work?
The short answer: it slows the breakdown of fresh gas and helps protect the fuel system while an engine sits, but it does not stop fuel from going stale forever. Briggs and Stratton says gas begins to degrade in as little as 30 days, and that stabilizer prevents the gum and varnish build-up that clogs a fuel system.
The tests agree on the limits. Oak Ridge National Laboratory aged regular E10 from the pump in sealed, partly filled 1-gallon cans kept outdoors in the shade, with and without three stabilizers (STA-BIL 360 Protection, Star Tron and a Lucas Safeguard conditioner), and had it tested at intervals up to 12 months. The untreated gas still met gasoline specifications at 12 months. Two of the three additives made the gas more resistant to oxidation, a margin the fuel did not need within that year; the report labels the samples A, B and C and does not say which product was which. Those were sealed cans, not a vented tank and carburetor left for a season.
Project Farm's conclusion was that none of the stabilizers kept fuel from becoming stale after 20 months; STA-BIL was only a little better than the rest on that, and its real advantage was corrosion. FortNine went further: its host concluded that fuel stabilizers do not generally help, that ethanol is the accomplice in storage problems, and that ethanol-free gas is the fix if you can get it; of the stabilizers, it singled out K100 and STA-BIL. So the honest case for a bottle like pick 1 is protection for the carburetor and tank over a season, not gas that stays new for years, and for gas you will burn within a year in a sealed can, Oak Ridge's result says you may not need one.
How to use fuel stabilizer in a lawn mower or snow blower
- Start with fresh gas. STA-BIL says to use its stabilizer only with fresh fuel and to treat gas as soon as you buy it.
- Add the dose, then the gas. STA-BIL's directions are to pour it in before adding gasoline, and Star brite says to add Star Tron just before you fill up; use the storage dose from the table above.
- Fill the tank. Briggs and Stratton says to store the machine filled with treated fuel; STA-BIL says 95 percent full.
- Run the engine a few minutes so treated fuel reaches the carburetor: Briggs and Stratton, Honda and STA-BIL all say to circulate it.
Briggs and Stratton says treated fuel removes the need to drain before storage and keeps fuel fresh for up to 24 months. Honda's engine storage advice adds two cautions: all stabilizers have a shelf life, and for long-term storage it prefers draining the tank and carburetor. Store the machine in a ventilated spot away from anything with a flame, such as a furnace, water heater or clothes dryer, as Honda advises. A snow blower that sits from March to December is inside the storage life pick 1 and pick 3 claim; for the machines themselves, see our best snow blowers and best 2-stage snow blowers, and for the rest of the shed, how to clean and store garden tools for winter.
Fuel stabilizer for a generator: stabilize or drain?
The short answer: for a gas generator, STA-BIL Storage (pick 1) in the tank, and in every can STA-BIL 360 Protection (pick 6), or pick 1 for a can that may sit past 12 months; for a backup unit you start only a few times a year, VP's ethanol-free fuel (pick 3); for a diesel unit, STA-BIL Diesel (pick 5). Then follow your manual on draining. The steps below are Honda's for its EU inverters; other makers' manuals govern their own units.
Generators are the hardest case, because a backup unit may sit for a year and then has to start the night the power goes out. Honda's advice for its EU inverter generators is the clearest we found, and it depends on how long the unit will sit: stabilized fresh fuel for 1 to 2 months, a drained carburetor for 2 to 12 months or any unit run less than once a month, and a drained tank and carburetor beyond a year, because even treated gasoline left in the fuel system can deteriorate. Honda also says to use fuel with no more than 10 percent ethanol, to add stabilizer each time you fill a portable can, and, if stabilized fuel has sat in a can for 12 months, passes on the EPA's suggestion to add it to a fairly full car tank. For choosing the generator, see our best inverter generators.
Fuel stabilizer for a string trimmer, blower or chainsaw
STA-BIL says its Storage formula works in 2-cycle gas and oil mixtures as well as 4-cycle engines. STIHL is stricter about its own tools: mix no older than 60 days, and preferably 30, even with a stabilizer, and run the tool dry if it will sit more than 30 days. That makes premixed, ethanol-free fuel the simpler answer for most 2-stroke owners, which is why pick 4 is here. If you do mix your own, mix only what you will use within STIHL's window. Our guides to the best gas leaf blowers and best chainsaws cover the tools.
Does fuel stabilizer fix old gas? Ethanol, stale fuel and what to do
No. Honda says stabilizers will not reconstitute stale fuel, and STA-BIL says its own will not restore old gasoline, only stop it degrading further. Project Farm's Star Tron sample shows the limit too: the listing says it can help rejuvenate old fuel, yet the 20-month sample would not light.
Ethanol is the reason small engines suffer. Honda says ethanol is corrosive and quickly attracts water from the air; Briggs and Stratton warns that E15 attracts moisture that separates into a layer of water and alcohol at the bottom of the tank; STIHL allows up to E10 in its engines. If you are not sure how old the gas in a mower is, TruFuel's advice before switching to canned fuel is to drain the old fuel first. For a can of old gas, Honda's page passes on the EPA's suggestion to add it to a car's tank that is fairly full.
From the team behind this guide
Spear Head Spade makes double-patented digging spades, not fuel additives, so none of our products is in this roundup. If a new spade is also on your list before the ground freezes, our spade finder matches one to your soil.
Frequently asked questions
How long does fuel stabilizer last?
Two clocks run. The bottle: STA-BIL says its products last 2 years after opening if tightly capped. The treated fuel: makers claim up to 24 months for STA-BIL Storage and 2 years for Star Tron, but STA-BIL's own FAQ warns that gas stored more than 12 months tends to lose ignitability, and Honda says to drain an engine that will sit more than a year.
Can you put too much fuel stabilizer in gas?
Within limits, no harm. STA-BIL says over-dosing is fine but not beyond 4 times the recommended amount, and to dilute the fuel if you have gone past that. Star brite says overdosing Star Tron is not harmful. STA-BIL says not to overtreat with its diesel formula.
Which is better, Sea Foam or STA-BIL?
For storage, STA-BIL. In Project Farm's five-year test the STA-BIL jar had no corrosion while the Sea Foam jar corroded heavily, and the generator started on STA-BIL-treated fuel without help but needed 21 shots of starting fluid on Sea Foam-treated fuel. FortNine rated Sea Foam worst on oxidation. Sea Foam's listing leads with fuel system cleaning.
Is Lucas fuel stabilizer better than STA-BIL?
No test we read has compared Lucas Fuel Stabilizer with STA-BIL Storage. Oak Ridge tested a different Lucas product, its Safeguard conditioner, next to STA-BIL 360 Protection, and did not say which sample was which. Lucas Fuel Stabilizer and STA-BIL Storage use the same dose, 1 ounce per 2.5 gallons, and both say they contain no alcohol. STA-BIL has five years of results from Project Farm behind it, which is why it is our pick.
When should you add fuel stabilizer?
When the gas is fresh, before the engine is put away. STA-BIL says to treat fuel as soon as you buy it, then run the engine 5 minutes; Star brite says to add Star Tron just before you fill up; Honda says to add stabilizer every time you fill a portable can. Bob Vila says it is not necessary for gas you will burn within a month or two.
Is it okay to use fuel stabilizer all the time?
Some are made for it. STA-BIL says to use 360 Protection at every fill-up and its diesel formula at every fill-up at the lighter in-season rate, and Star brite says to add Star Tron before each fill-up. Oak Ridge found untreated gas in sealed cans stayed within specification for 12 months, so for gas you use quickly it is optional.
Do I need fuel stabilizer with ethanol-free gas?
Less often. Ethanol-free canned fuels such as VP and STIHL MotoMix are sold ready to store: VP says 2 years in the tank and STIHL up to two years for MotoMix. FortNine's advice is to fill with ethanol-free gas before storage if you can. For ethanol-free pump gas going into long storage, STA-BIL says its Storage formula works in non-ethanol gasoline as well.
