Prices verified May 28 · Always confirm at the retailer before buying.
The STA-BIL Storage wins for garage storage — $10.99 treats 40 gallons and keeps fuel fresh 24 months. Sea Foam is better for cleaning dirty injectors.
The Verdict
Winner
STA-BIL Storage Fuel Stabilizer
STA-BIL Storage Fuel Stabilizer, 16 oz vs Sea Foam Motor Treatment, 16 oz Pack of 3, side by side
Pros:
- Keeps gasoline fresh up to 24 months
- Prevents gum and varnish in stored engines
- Works with ethanol blends up to E85
- Easy to measure with dual-cap bottle
- Live Amazon coupon available at time of review
Cons (honest weight):
- Only stabilizes fuel — does not clean injectors
- Single-use scenario: not for daily driver maintenance
Pros:
- Deep cleans entire fuel system
- Restores lost power and MPG
- Works in both gas and diesel engines
- Can be used as oil treatment
Cons (honest weight):
- Requires multiple bottles for deep clean
- More expensive per ounce than stabilizers
Where each one wins
10 dimensions scored head-to-head. STA-BIL Storage takes 3; Sea Foam takes 3.
| Dimension | STA-BIL Storage Fuel Stabilizer, 16 oz | Sea Foam Motor Treatment, 16 oz Pack of 3 | Winner |
|---|---|---|---|
| Primary PurposeDesigned for different jobs — storage vs cleaning. | Storage stabilization | Fuel system cleaning | Tie |
| Price per OunceSea Foam 3-pack costs less per ounce. | $0.69/oz | $0.62/oz | Sea Foam |
| Stabilization DurationBoth stabilize fuel for up to 2 years. | 24 months | 2 years (24 months) | Tie |
| Cleaning AbilitySea Foam is the only cleaner. | None (stabilizer only) | Cleans injectors, carburetors, valves | Sea Foam |
| Versatility (Fuel + Oil)Sea Foam works in both fuel and crankcase. | Fuel only | Fuel and oil systems | Sea Foam |
| User RatingBoth highly rated with tens of thousands of reviews. | 4.8/5 (31,041 reviews) | 4.8/5 (29,116 reviews) | Tie |
| Ethanol CompatibilitySTA-BIL explicitly supports up to E85. | E10 through E85 | E10 and E85 | STA-BIL Storage |
| Engine Type CoverageBoth cover gasoline; Sea Foam also covers diesel. | All gasoline engines, 2-cycle compatible | Gasoline and diesel | Tie |
| Application EaseSTA-BIL's double-cap design simplifies dosing. | Dual-cap bottle for precise measuring | Standard bottle with graduated markings | STA-BIL Storage |
| Value per Gallon TreatedSTA-BIL costs less per gallon treated. | $0.27/gal | $0.50/gal (assuming 1 oz treats 2.5 gal) | STA-BIL Storage |
| Overall | 3 wins | 3 wins | Tie |
Primary Purpose — Storage vs. Cleaning
STA-BIL Storage is engineered exclusively for preserving fuel during inactivity. It prevents gum, varnish, and corrosion that form when gasoline sits.
Sea Foam Motor Treatment is a multi-purpose additive that cleans fuel systems and stabilizes fuel. The choice comes down to your goal: storage or restoration.
Price per Ounce — Sea Foam Is More Economical
Sea Foam costs $0.62 per ounce in the 3-pack, while STA-BIL runs $0.69 per ounce. The 3-pack gives you 48 total ounces for $29.99, compared to STA-BIL's 16 ounces for $10.99.
If you need bulk additive, Sea Foam offers better value per ounce.
Stabilization Duration — Both Last Two Years
Both products keep fuel fresh for up to 24 months after treatment. STA-BIL claims 24 months for storage, and Sea Foam states up to 2 years.
Either will preserve fuel through a typical winter or off-season. For shorter periods, both work well.
Cleaning Ability — Sea Foam Is the Only Cleaner
STA-BIL does not clean fuel systems; it only stabilizes. Sea Foam contains detergents that dissolve soft varnish and carbon deposits from injectors, carburetors, and combustion chambers.
If your engine runs rough or has lost power, Sea Foam can restore performance.
Versatility — Sea Foam Works in Oil Too
Sea Foam can be added to engine oil to clean sludge and deposits. STA-BIL is strictly a fuel additive.
Sea Foam offers added value for maintaining the entire engine, not just the fuel system.
User Ratings — Both Are Highly Trusted
STA-BIL holds a 4.8 average from 31,041 reviews; Sea Foam also 4.8 from 29,116 reviews. Both products enjoy strong customer satisfaction.
The review volume indicates reliability and consistent results across many vehicle types.
Ethanol Compatibility — STA-BIL Supports Higher Blends
STA-BIL explicitly works with ethanol blends up to E85. Sea Foam is compatible with E10 and E85 but does not emphasize higher blends.
If you use ethanol-rich fuel, STA-BIL offers more assurance.
Engine Type Coverage — Diesel Support Ties
Both cover gasoline engines. STA-BIL is safe for all gasoline engines including 2-cycle. Sea Foam also works in diesel engines, giving it a broader application range.
For diesel owners, Sea Foam is the clear choice.
Application Ease — STA-BIL's Dual Cap Simplifies Dosing
STA-BIL features two caps: a small one for precise small doses and a large one for pouring. Sea Foam uses a standard bottle with graduated markings.
The dual-cap design makes measuring easier, especially for small engines.
Value per Gallon Treated — STA-BIL Treats More for Less
At $0.27 per gallon treated, STA-BIL is significantly cheaper per gallon than Sea Foam at $0.50. If your primary need is stabilizing large fuel volumes, STA-BIL stretches your dollar further.
Which should you buy?
| Your situation | Pick | Why |
|---|---|---|
| Storing a car for winter | STA-BIL Storage Fuel Stabilizer, 16 oz | STA-BIL stabilizes fuel for 24 months, ensuring a quick spring start. |
| Cleaning rough idle and lost power | Sea Foam Motor Treatment, 16 oz Pack of 3 | Sea Foam cleans injectors and valves to restore performance. |
| Boat storage over the off-season | STA-BIL Storage Fuel Stabilizer, 16 oz | STA-BIL prevents moisture-related fuel degradation in marine tanks. |
| Daily driver maintenance | Sea Foam Motor Treatment, 16 oz Pack of 3 | Sea Foam can be used every 3,000 miles to keep the fuel system clean. |
| Small engine (lawn mower, snow blower) | STA-BIL Storage Fuel Stabilizer, 16 oz | STA-BIL's 16 oz bottle treats 40 gallons, enough for multiple small engines. |
| Generator storage after use | STA-BIL Storage Fuel Stabilizer, 16 oz | Stabilizing fuel in generators prevents carburetor clogs from stale gas. |
| Diesel engine maintenance | Sea Foam Motor Treatment, 16 oz Pack of 3 | Sea Foam is safe for diesel engines; STA-BIL is gasoline only. |
| Oil sludge removal | Sea Foam Motor Treatment, 16 oz Pack of 3 | Sea Foam can be added to oil to clean crankcase deposits. |
STA-BIL stabilizes fuel for 24 months, ensuring a quick spring start.
Sea Foam cleans injectors and valves to restore performance.
STA-BIL prevents moisture-related fuel degradation in marine tanks.
Sea Foam can be used every 3,000 miles to keep the fuel system clean.
STA-BIL's 16 oz bottle treats 40 gallons, enough for multiple small engines.
Stabilizing fuel in generators prevents carburetor clogs from stale gas.
Sea Foam is safe for diesel engines; STA-BIL is gasoline only.
Sea Foam can be added to oil to clean crankcase deposits.
What if neither is right?
Lucas Oil Fuel Treatment, 1 Quart
$11.59
Budget-friendly lubricant for high-mileage engines, treats up to 64 gallons.
Star Tron Enzyme Fuel Treatment Concentrate
$21.06
Enzyme-based formula that disperses water and works with all fuels.
Red Line 60103 SI-1 Complete Fuel System Cleaner
$15.99
Highest PEA content for aggressive cleaning of heavily carbonized engines.
Frequently Asked Questions
STA-BIL vs Sea Foam: Which is better for storing a car?
STA-BIL Storage is better for storing a car. It stabilizes gasoline for up to 24 months and prevents gum and varnish. Sea Foam also stabilizes fuel for 2 years, but its main purpose is cleaning, not long-term storage. For winter storage or an idle vehicle, choose STA-BIL.
Can I use both STA-BIL and Sea Foam in the same tank?
Yes, you can use both products in the same fuel tank. They serve different functions: STA-BIL stabilizes and Sea Foam cleans. Add them separately according to each product's directions. Some users add Sea Foam for cleaning and then use STA-BIL for storage.
Which one is more cost-effective per gallon treated?
STA-BIL is more cost-effective at $0.27 per gallon treated. Sea Foam costs about $0.50 per gallon. For large volumes of fuel, STA-BIL stretches your money further. However, Sea Foam offers extra cleaning benefits that justify the higher cost for some users.
Do these products work with ethanol-blended fuels?
STA-BIL explicitly works with ethanol blends up to E85, including E10 and E15. Sea Foam is also compatible with E10 and E85. Both prevent phase separation and corrosion caused by ethanol.
How often should I add fuel additive to my vehicle?
For storage, add STA-BIL when you fill the tank before parking. For cleaning, add Sea Foam every 3,000 miles or whenever you notice rough idling or reduced power. Always follow the dosage instructions on the bottle.
How we compared. We analyzed 60,157 verified Amazon reviews, product specifications, and manufacturer data for both products. Prices update weekly from Amazon. Published lab data from video reviewers and independent forums were considered where available.
Who wrote this and where's the data from?
Mubboo Editorial Team — independent US-market consumer research. Picks reflect verified buyer data across 60,000+ reviews and manufacturer specifications.