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Frequently Asked Questions
How long does STA-BIL keep fuel fresh?
A STA-BIL fuel stabilizer treatment keeps fuel fresh for up to 24 months, per Gold Eagle, when added to fresh fuel with the tank kept nearly full. Real-world results vary with storage conditions.
How much STA-BIL do I add per gallon?
The ratio is 1 oz per 2.5 gallons of gasoline. A 15-gallon car tank needs 6 oz; a 5-gallon mower can needs 2 oz. The 16 oz bottle treats up to 40 gallons total.
Will STA-BIL fix old, stale gas?
No. Gold Eagle states it must be added to fresh fuel. It preserves fuel, it does not restore fuel that has already degraded. Drain stale fuel and refill before treating.
Is STA-BIL safe for ethanol fuel?
Yes. The manufacturer rates it effective in all gasoline and ethanol blends from E-10 through E-85, and in both 2-cycle and 4-cycle engines.
Do I need to drain the tank before storing with STA-BIL?
No, that is the point of the product. Fill the tank to about 95% with fresh fuel, add STA-BIL, run the engine 5 minutes, then store.
How long is an opened bottle good for?
Up to 2 years after opening, per Gold Eagle. Mark the opening date on the bottle so you know.
STA-BIL Fuel Stabilizer Review: Is the 16 oz Bottle Worth It?
Table of Contents
You parked the boat in October. You pull it out in April, turn the key, and the engine coughs, sputters, and dies. The culprit is usually not the battery or the spark plugs. It is the fuel. Gold Eagle, the company behind STA-BIL, states that gasoline begins to break down in as little as 30 days after leaving the refinery. A fuel stabilizer exists for exactly this problem: treat fresh fuel before storage so the engine starts when the season turns.
The short answer: STA-BIL fuel stabilizer (the Storage formula) is the default choice for seasonal storage because the dosage math is simple (1 oz treats 2.5 gallons) and Gold Eagle rates treated fuel as fresh for up to 24 months. The 16 oz bottle treats up to 40 gallons, which covers most cars, boats, and a season of small engines. It will not fix fuel that has already gone stale. It only preserves fuel that is still fresh.
Quick Pick: STA-BIL Fuel Stabilizer
| Pick | Product | Best For | Check Price |
|---|---|---|---|
| Best Overall | STA-BIL Storage Fuel Stabilizer, 16 oz | Cars, boats, and mowers going into seasonal storage | Check Price on Amazon |
| Best Value Size | STA-BIL Storage Fuel Stabilizer, 16 oz | One bottle treats up to 40 gallons, a full season for most households | Check Price on Amazon |
| Best for Small Engines | STA-BIL Storage Fuel Stabilizer, 16 oz | Mowers, snow blowers, generators, 2-cycle engines | Check Price on Amazon |
What STA-BIL Storage Actually Does
STA-BIL Storage is an alcohol-free fuel additive made by Gold Eagle Co. (model 22207). Its job is narrow and well-defined: slow the oxidation and evaporation that turn stored gasoline into gum and varnish. Per the manufacturer, it keeps gasoline fresh for up to 24 months and works in all gasoline blends from E-10 through E-85.
That matters because modern ethanol-blended fuel is hygroscopic, it pulls moisture from the air. In a half-empty tank sitting for months, that moisture plus oxidation produces the deposits that clog carburetors and injectors. STA-BIL’s formula includes corrosion inhibitors that protect the fuel system during the sit, which is why Gold Eagle positions it as storage insurance rather than a performance additive.
It is worth being precise about what it is not: this is not a fuel system cleaner. If your engine already runs rough from carbon deposits, a cleaner (not a stabilizer) is the right product. We compared the two jobs head-to-head in our fuel stabilizer vs fuel system cleaner guide.
How to Use It: Dosage in Three Steps
The dosage is the product’s strongest practical feature: no measuring cup math beyond one ratio.
1. Measure: 1 oz per 2.5 gallons. The bottle’s long neck has measurement markings; squeeze to the level you need. A typical car with a 15-gallon tank needs 6 oz. A 5-gallon gas can for the mower needs 2 oz.
2. Add to fresh fuel, then fill the tank to 95%. Two details matter here. First, STA-BIL only preserves fuel that is still fresh. Add it on your last fill-up before storage, not months later. Second, a nearly full tank leaves little air space, which limits the moisture condensation that ethanol blends invite.
3. Run the engine for 5 minutes. This circulates treated fuel through the lines, carburetor or injectors, and filter, the whole fuel system, not just the tank. Then shut it down and store.
One 16 oz bottle treats up to 40 gallons total, so a single bottle typically covers a car’s winter storage plus a few small engines. Once opened, Gold Eagle says the bottle stays good for up to 2 years. Mark the opening date on the back of the package.
Who Should Buy It (and Who Should Not)
Buy it if: you store anything with a gasoline engine for 30 days or longer: a classic car over winter, a boat between seasons, a motorcycle, a lawn mower, a snow blower, or a generator. It is safe for 2-cycle and 4-cycle engines alike, per the manufacturer.
Skip it if: your equipment runs year-round (the fuel never sits long enough to degrade), you run only diesel (this is a gasoline product), or the fuel in the tank is already months old and smells sour. No stabilizer reverses stale fuel. In that case, drain and refill with fresh fuel first.
Honest Limitations
Three things to know before buying. First, the 24-month freshness figure is the manufacturer’s rating under proper storage conditions (fresh fuel, full tank, treated system), and real-world results vary with temperature swings and tank sealing. Second, STA-BIL Storage will not restore old gasoline; Gold Eagle is explicit that it must be added to fresh fuel. Third, it does not clean existing deposits: gummed-up carburetors need mechanical cleaning or a dedicated cleaner, not a stabilizer.
None of these are deal-breakers for the product’s actual job. They are the difference between buying it for the right reason and being disappointed for the wrong one.
The Verdict: Should You Buy the 16 oz Bottle?
If you store gasoline-powered equipment for the off-season, yes. The 16 oz STA-BIL fuel stabilizer bottle is the right size for most households, enough for a car plus small engines, simple dosage, and a 24-month freshness rating from the manufacturer. Add it to fresh fuel on your last run of the season, run the engine five minutes, and the spring start-up is one less thing to worry about. It is a small, cheap insurance policy against the most common storage failure there is: stale fuel.
Related reading: our car maintenance checklist covers seasonal storage prep beyond the fuel tank.
