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The generator sits in the garage all winter, and when the storm knocks the power out it coughs and dies on old gas. The question is how to use fuel stabilizer, and the short answer is that you pour it into the tank before you add gas, at the ratio the bottle states, and run the engine for 5 minutes so the treated fuel reaches the whole system. This guide walks through the ratios on the 4 stabilizers below, and what each one handles.
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How to use fuel stabilizer in a generator
Every listing here gives the same steps, with a different ratio. Pour the stabilizer directly into the fuel tank before adding gasoline, use the ratio the bottle states for the gallons you are treating, and after adding the fuel run the engine for 5 minutes to treat the entire fuel system. Generators run outdoors only, far from doors and windows, because of carbon monoxide. The table below shows the ratio and the storage time each listing states.
| Stabilizer | Ratio stated | Storage stated | Amazon |
|---|---|---|---|
| STA-BIL Storage | 1 oz for every 2.5 gallons | Fuel fresh for up to 24 months | |
| STA-BIL 360 Marine | 1 oz for every 10 gallons | Stabilizes fuel in-season when idle | |
| Star Tron Enzyme | 1 fluid ounce per 6 gallons | Stabilizes fuel up to 2 years | |
| Star Tron 32 oz | No ratio stated in the title | Treats up to 512 gallons |
Stabilizers that treat the fuel
Getting the ratio right is the step that needs the bottle in hand, so the 4 stabilizers below carry that part of the job, from a storage formula for winter to a marine formula that cleans as it treats.
| # | Product | Solar Score | Buy |
|---|---|---|---|
| 1 |  STA-BIL Storage Fuel Stabilizer | 9.7/10 | Buy on Amazon |
| 2 |  Star Tron Fuel Treatment | 9.7/10 | Buy on Amazon |
| 3 |  STA-BIL 360 Marine Treatment | 9.6/10 | Buy on Amazon |
| 4 |  Star Tron Enzyme Fuel Treatment | 9.6/10 | Buy on Amazon |
STA-BIL Storage Fuel Stabilizer
A 1-gallon storage stabilizer that treats 320 gallons and keeps fuel fresh for up to 24 months.
Pros
- Keeps fuel fresh for up to 24 months during storage
- Treats 320 gallons from a 1-gallon bottle
- Helps protect against corrosion and ethanol damage
- Clear directions: 1 oz for every 2.5 gallons, then run the engine for 5 minutes
Cons
- No warranty term with a stated length is given
- Made for storage, not for in-season cleaning
- No cleaning or water removal is stated for this formula
Detailed Review
The listing states a 1-gallon bottle that treats 320 gallons, fuel kept fresh for up to 24 months during storage, protection against corrosion and ethanol damage, and directions to pour into the tank before adding gasoline, use 1 oz for every 2.5 gallons of gas, and run the engine for 5 minutes to treat the entire fuel system. It states an expiration of 2 years from opening, or 5 years from the date of production, read from a 5-digit code on the back of the bottle. The spec table lists an item weight of 0.000625 pounds, which does not match a 1-gallon bottle; the title and bullets are the reliable figures here.
Who it's for: owners storing a generator, boat or outdoor equipment over winter who want the longest stated storage time here. Who should skip it: anyone who wants in-season cleaning or water removal, which the marine formula states.
Its Solar Score of 9.7/10 comes from performance 32/35, build 22/25, value 21/25, safety 7/10 and warranty 0/5: 82 of 100 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Size | 1 gallon, treats 320 gallons |
|---|---|
| Ratio | 1 oz for every 2.5 gallons |
| Storage | Fuel fresh for up to 24 months |
| Protection | Corrosion and ethanol damage |
Taken from the seller's listing on 13 November 2026. Capacity and output figures are rated by the manufacturer.
Safety and Warranty
What this listing states. Protection against corrosion and ethanol damage stated, so safety scores 7 of 10. No warranty term, so warranty scores zero. See How We Pick.
Follow the manual. Connect and use the product as the maker describes, stay within every stated rating, and read the manual before first use.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.
Star Tron Fuel Treatment
A 32 oz enzyme fuel treatment that treats up to 512 gallons and stabilizes fuel up to 2 years.
Pros
- 32 oz treats up to 512 gallons
- 1 fluid ounce per 16 gallons of fuel
- Stabilizes fuel up to 2 years
- Enzyme technology for engines that start more reliably
Cons
- No warranty term is stated; the listing gives a 30-day return for a refund
- No Mercury Marine spec is stated
- No corrosion claim is stated
- Only the 32 oz size is stated for this listing
Detailed Review
The listing states a 32 oz concentrated enzyme fuel treatment that treats up to 512 gallons, stabilizes fuel up to 2 years, and can help rejuvenate old, sub-spec fuel. It lists 1 fluid ounce per 16 gallons, enzyme technology, phase separation prevention, and a weight of 1.9 pounds. The warranty line states a 30-day return for a refund of the purchase price, which is a return window, not a warranty term.
Who it's for: owners with a large tank who want the largest treat volume per bottle. Who should skip it: anyone who wants a stated warranty term.
Its Solar Score of 9.7/10 comes from performance 32/35, build 22/25, value 22/25, safety not scored (non-powered gear) and warranty 0/5: 76 of 90 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Treats | Up to 512 gallons |
|---|---|
| Ratio | 1 fluid ounce per 16 gallons |
| Storage | Up to 2 years |
| Size | 32 oz, 1.9 pounds |
Figures as published on the retailer listing, collected 10 November 2026. Performance figures are manufacturer rated.
Safety and Warranty
What this listing states. This product does not plug in or run on a battery, so safety is not part of its score. No warranty term, so warranty scores zero. See How We Pick.
Follow the manual. Connect and use the product as the maker describes, stay within every stated rating, and read the manual before first use.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.
STA-BIL 360 Marine Treatment
A 32 oz marine treatment that cleans fuel systems, removes water and treats 320 gallons.
Pros
- Cleans the fuel system, injectors, lines and fuel pumps
- Removes water, gum and varnish
- Treats 320 gallons from a 32 oz bottle
- Clear directions: 1 oz for every 10 gallons, then run the engine for 5 minutes
Cons
- No warranty term is stated
- Made for marine engines and in-season use, not long storage
- No storage time in months is stated for this formula
- No ethanol damage figure is stated beyond corrosion protection
Detailed Review
The listing states a 32 oz bottle that treats 320 gallons, cleaning of the entire fuel system with PEA additives, removal of water, gum and varnish, rust and corrosion protection, and directions to pour directly into the fuel tank before fill up, use 1 oz for every 10 gallons of fuel, and run the engine for 5 minutes to treat the entire fuel system. It stabilizes fuel in-season when a watercraft is idle, and the listing pairs it with STA-BIL Storage for winter storage needs.
Who it's for: boat and marine engine owners who want cleaning and water removal during the season. Who should skip it: anyone storing fuel for months, who should use the storage formula instead.
Its Solar Score of 9.6/10 comes from performance 30/35, build 21/25, value 21/25, safety 7/10 and warranty 0/5: 79 of 100 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Size | 32 oz, treats 320 gallons |
|---|---|
| Ratio | 1 oz for every 10 gallons |
| Cleaning | Fuel system, injectors, lines, pumps |
| Removes | Water, gum, varnish |
Taken from the seller's listing on 13 November 2026. Capacity and output figures are rated by the manufacturer.
Safety and Warranty
What this listing states. Removes water and protects against rust and corrosion stated, so safety scores 7 of 10. No warranty term, so warranty scores zero. See How We Pick.
Follow the manual. Connect and use the product as the maker describes, stay within every stated rating, and read the manual before first use.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.
Star Tron Enzyme Fuel Treatment
An enzyme fuel treatment that stabilizes fuel up to 2 years and helps rejuvenate old gasoline.
Pros
- Stabilizes fuel up to 2 years and helps rejuvenate old, sub-spec fuel
- Works in all engines and all fuels, from cars to boats, RVs and lawn mowers
- Helps prevent ethanol problems and phase separation
- Made in the USA since 1973
Cons
- No warranty term is stated
- No bottle size in gallons is stated for this listing
- No corrosion protection figure is stated
- Pack of 12 with 1 oz bottles means measuring per bottle
Detailed Review
The listing states an enzyme fuel treatment that stabilizes fuel up to 2 years, helps rejuvenate old, sub-spec fuel, prevents ethanol problems, cleans gum, carbon and varnish deposits, helps prevent phase separation by dispersing water as submicron-sized droplets, and works in all engines and all fuels. It states 1 fluid ounce per 6 gallons of fuel, a size of 1 oz in a pack of 12, a weight of 0.75 pounds, and that the products have been made in the USA since 1973.
Who it's for: owners with old fuel in any engine who want one treatment for cars, boats, RVs and mowers. Who should skip it: anyone who wants a stated storage time in months or a single large bottle.
Its Solar Score of 9.6/10 comes from performance 29/35, build 21/25, value 20/25, safety 7/10 and warranty 0/5: 77 of 100 points, placed on our 9.2 to 9.8 scale.
Key Specifications
| Ratio | 1 fluid ounce per 6 gallons |
|---|---|
| Storage | Stabilizes fuel up to 2 years |
| Size | 1 oz, pack of 12 |
| Works in | All engines and all fuels |
Taken from the seller's listing on 13 November 2026. Capacity and output figures are rated by the manufacturer.
Safety and Warranty
What this listing states. Prevents ethanol problems and phase separation stated, so safety scores 7 of 10. No warranty term, so warranty scores zero. See How We Pick.
Follow the manual. Connect and use the product as the maker describes, stay within every stated rating, and read the manual before first use.
This is general buying information, not professional advice. Follow each product manual and local rules, and see our Safety Disclaimer.
As an Amazon Associate I earn from qualifying purchases.
How to choose a fuel stabilizer for a generator
Match the stabilizer to the tank and the season: ratio, storage time, and what else the formula handles.
Match the ratio to the tank
The ratio decides how much bottle you need for the tank. STA-BIL Storage states 1 oz for every 2.5 gallons and treats 320 gallons from a 1-gallon bottle, STA-BIL 360 Marine states 1 oz for every 10 gallons and treats 320 gallons from a 32 oz bottle, and Star Tron states 1 fluid ounce per 6 gallons. The Star Tron 32 oz bottle states it treats up to 512 gallons. See the best fuel stabilizers for generators when the tank size is still undecided.
Match the storage time to the season
Storage time decides which bottle fits the layup. STA-BIL Storage keeps fuel fresh for up to 24 months during storage, and Star Tron stabilizes fuel up to 2 years. STA-BIL 360 Marine is made for in-season use, stabilizing fuel when the watercraft is idle, and the listing pairs it with STA-BIL Storage for winter. See the fuel stabilizer vs fuel cleaner guide for the difference between storing and cleaning.
Check what else the formula handles
Some formulas do more than stabilize. STA-BIL Storage helps protect against corrosion and ethanol damage, STA-BIL 360 Marine cleans fuel systems and injectors and removes water, and Star Tron helps prevent ethanol problems and phase separation while cleaning gum, carbon and varnish deposits. See the best fuel stabilizers and cleaners for formulas that do both jobs.
FAQ: power away from the grid
How do you use fuel stabilizer?
Pour it directly into the fuel tank before adding gasoline, at the ratio the bottle states, then run the engine for 5 minutes to treat the entire fuel system. Both STA-BIL listings give these steps, and the Star Tron listing gives 1 fluid ounce per 6 gallons.
How much stabilizer do I need per gallon?
It depends on the bottle: STA-BIL Storage states 1 oz for every 2.5 gallons, STA-BIL 360 Marine states 1 oz for every 10 gallons, and Star Tron states 1 fluid ounce per 6 gallons. Measure the gallons in the tank first, then pour to the ratio.
How long does stabilized fuel last?
STA-BIL Storage keeps fuel fresh for up to 24 months during storage, and Star Tron stabilizes fuel up to 2 years. STA-BIL also states an expiration of 2 years from opening, or 5 years from the date of production.
Does fuel stabilizer work in old gas?
Star Tron states it stabilizes fuel up to 2 years and can help rejuvenate old, sub-spec fuel, and it cleans gum, carbon and varnish deposits. STA-BIL Storage is made for fuel in vehicles, boats and outdoor power equipment that are not in use.
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