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Has your car been sitting with gas in the tank, waiting in your driveway or garage for months without being driven? If you didn’t add a fuel stabilizer into your gas tank before your car began to sit, you could discover an unpleasant surprise when you do finally get behind the wheel again. Over time, both gasoline and diesel fuel can break down and deteriorate. And as these fuels age, they can leave behind gummy, gunked-up deposited throughout your engine. But if you use a fuel stabilizer, you can keep your fuel fresh, properly balanced, and perfectly stable with no evaporation — and no left-behind deposits in your engine.
Fuel stabilizers can extend the life of your car’s fuel for as long as two years. They can even be used for gas you’re storing in fuel cans or for your lawnmower, snowblower, chainsaw, and other gas-powered items. If you’re hoping to maintain great performance and long-term functionality, a fuel stabilizer is a must-have. Check out our picks for the best fuel stabilizers, plus our tips for choosing a great stabilizer, right here.
Spring had sprung and I opened the garage door and was finally able to roll out my old Mustang. Over the winter, I installed a new cylinder head and carburetor, and after sitting dormant for six months, I was eager to fire it up. After reconnecting the battery, I checked the fuel line and made sure the coolant was topped off. Finally, I climbed into the driver’s seat, pumped the gas, and turned the key. As the starter engaged, I realized I was about to run old fuel through a new carburetor. Fuel that was now more than six months old. A new fuel filter would help, but if any gunk got past, I’d be looking at flushing the tank, fuel line, and maybe a carburetor rebuild.
Fortunately, I had added a fuel stabilizer before I stored the Mustang. More proof of better living through chemistry, fuel stabilizers extend the shelf life of gasoline up to two years — even longer if you buy non-ethanol gas. Used properly they prevent gasoline from breaking down and it can be left in gas tanks, vehicles, or small engines. If you live in a four-season climate, a fuel stabilizer is a must-have for storing gasoline or gas-powered engines for an extended period of time. To help choose the right one for your needs, I put together this helpful guide.
Star Tron's Enzyme Fuel Treatment
- Highly concentrated — one ounce treats 16 gallons
- Specifically designed for ethanol fuels
- Works great as a fuel stabilizer and fuel system treatment
- One of the more expensive additives
- Bottle shape makes it hard to pour
STA-BIL Fuel Stabilizer
- Ideal for long term storage — can stabilize gas for up to two years
- Removes water from the fuel system
- Works great with any gasoline engine
- Does not lubricate or clean fuel systems
Lucas Oil 10303 Fuel Stabilizer
- Cleans and lubricates your entire fuel system
- Works great with any gasoline engine
- Good for ethanol and non-ethanol gasoline
- Requires a higher concentration than other stabilizers
Our Methodology
Fuel stabilizers are like beer. They all work the same way but some have different ingredients. The difference comes down to your specific needs. Some fuel stabilizers are better for winterizing a vehicle or putting it in long-term storage. Other stabilizers work for up to six months and are formulated for small engines like a lawnmower or snowblower. Then there are stabilizers which are better at cleaning and lubricating fuel systems but aren’t recommended for long-term storage. With that in mind, I researched a number of fuel stabilizers to find a good cross-section of the different types of additives. Finally, I read professional and individual reviews and evaluated the fuel stabilizers based on my experience to narrow down this list. The goal was to present the best options so you can make an informed choice.
If you’d like to know more about how we research products, check out our set of guidelines for reviewing and recommending products and services.
Why Trust Us
Our reviews are driven by a combination of hands-on testing, expert input, “wisdom of the crowd” assessments from actual buyers, and our own expertise. We always aim to offer genuine, accurate guides to help you find the best picks.
Learn moreSpecs
- Cures and prevents ethanol fuel problems
- Good for everyday use and stabilizes fuel for up to two years
- Cleans fuel systems of carbon deposits, gums, and varnish for maximum performance, increased fuel efficiency, and reduced emissions
- Concentrated formula — one ounce treats up to 16 gallons
- Safe for 2- and 4-cycle engines
Pros
- Highly concentrated — one ounce treats 16 gallons
- Specifically designed for ethanol fuels
- Works great as a fuel stabilizer and fuel system treatment
- Six pockets
Cons
- One of the more expensive additives
- One of the more expensive additives
Pros
Highly concentrated — one ounce treats 16 gallons
Specifically designed for ethanol fuels
Works great as a fuel stabilizer and fuel system treatment
Cons
One of the more expensive additives
Bottle shape makes it hard to pour
Specs
- Prevents ethanol fuel problems
- Stabilizes fuel for up to two years
- Prevents gum, varnish, rust, and corrosion in your fuel tank
- One ounce treats up to 2.5 gallons of gasoline
- Safe for 2- and 4-cycle engines
Pros
- Can stabilize gas for up to two years
- Specifically designed to remove water from the fuel system
- Works great with any gasoline engine
- Six pockets
Cons
- Does not lubricate or clean fuel systems
Pros
Can stabilize gas for up to two years
Specifically designed to remove water from the fuel system
Works great with any gasoline engine
Cons
Does not lubricate or clean fuel systems
Specs
- Safe for all grades of gasoline including ethanol and non-ethanol blends
- Cleans and lubricates your entire fuel system
- Stabilizes gasoline for up to one year
- One ounce treats one gallon of gasoline
- Safe for 2- and 4-cycle engines
Pros
- Cleans and lubricates your entire fuel system
- Works great with any gasoline engine
- Good for ethanol and non-ethanol gas
- Six pockets
Cons
- Has a high stabilizer-to-gallon ratio (one ounce to one gallon)
Pros
Cleans and lubricates your entire fuel system
Works great with any gasoline engine
Good for ethanol and non-ethanol gas
Cons
Has a high stabilizer-to-gallon ratio (one ounce to one gallon)
Specs
- Best-selling brand of premium gas-line antifreeze
- Very inexpensive
- Absorbs five times more water than regular gas dryers
- Prevents rust and corrosion
- 12 ounces treats up to 20 gallons of fuel
Pros
- Great at removing water from the fuel system
- Works great on any gasoline or diesel engine
- Good for any fuel type
- Six pockets
Cons
- Not good for long-term storage
Pros
Great at removing water from the fuel system
Works great on any gasoline or diesel engine
Good for any fuel type
Cons
Not good for long-term storage
Specs
- 100 percent pure petroleum
- Cleans out gum and varnish deposits in addition to other contaminants
- Lubricates upper and protects fuel systems and upper cylinders
- Works in crankcase oil to liquefy harmful residues and deposits
- Stabilizes gas and diesel fuels for up to two years
Pros
- Easy and simple to use kit
- Cleans and lubricates fuel systems, carburetors, and fuel injectors
- Works great on any gasoline or diesel engine
- Good for any fuel type
Cons
- Not good for long term storage
Pros
Easy and simple to use kit
Cleans and lubricates fuel systems, carburetors, and fuel injectors
Works great on any gasoline or diesel engine
Good for any fuel type
Cons
Not good for long term storage
Specs
- Deep cleans the entire system and lubricates engine parts
- Enhances your motor oil's effectiveness
- Formulated to help maximize engine protection and performance
- Works with modern gasoline engines such as turbo, direct injection, and hybrid vehicles
- One bottle treats up to 35 gallons
Pros
- Formulated for modern gasoline engines
- Lubricates engine parts, reducing friction and improving fuel economy
- Redesigned bottles are compatible with cap-less fuel tanks
Cons
- Not a viable option for short or long term storage
Pros
Formulated for modern gasoline engines
Lubricates engine parts, reducing friction and improving fuel economy
Redesigned bottles are compatible with cap-less fuel tanks
Cons
Not a viable option for short or long term storage
Specs
- Formulated to clean the entire fuel system
- Reduces deposit-related engine knocking and pinging
- Penetrates and removes the most stubborn deposits to restore fuel economy, horsepower, and throttle response
- One bottle treats up to 20 gallons
- Recommended for use every 10,000 miles
Pros
- Completely cleans the entire fuel system
- Lowers hydrocarbon, NOx, and CO emissions
- Works great with any gasoline engine
- Stabilizes fuel and is good for any fuel type including ethanol, diesel, and biofuel
Cons
- Not suitable for use in long term storage
Pros
Completely cleans the entire fuel system
Restores lost performance and reduces engine knocking and pinging
Lowers hydrocarbon, NOx, and CO emissions
Stabilizes fuel and is good for any fuel type including ethanol, diesel, and biofuel
Cons
Not suitable for use in long term storage
Our Verdict
Star Tron's Enzyme Fuel Treatment takes the win because of its combination of additives for stabilizing fuel and lubricating fuel systems. However, you won’t go wrong with any of these fuel stabilizers. The STA-BIL Fuel Stabilizer is a great value and a trusted brand used for over 60 years. And the Lucas Oil 10303 Fuel Stabilizer does a great job of cleaning and lubricating your fuel system.
What to Consider When Buying a Fuel Stabilizer
Length of Time
The first thing to consider is the length of time for storage. Several of the fuel stabilizers on this list provide up to 24 months of protection. But if you only need something for the winter months or half a year, you may want a stabilizer that offers other benefits like cleaning and lubricating the fuel system.
Ease of Use
Some fuel stabilizers come in a bottle that you dump in a tank with up to 20 gallons of fuel. But many provide a mix ratio like one ounce to 10 gallons of gas. This is when ease of use becomes important, specifically how easy it is to measure the right amount of fuel stabilizer for adequate protection.
Pro tip: Your significant other will not appreciate it if you use their measuring cups, medicine syringes, shot glasses, or other household containers to dose out the correct amount of fuel stabilizer. Trust me on this one.
Compatibility
Make sure you’re using a fuel stabilizer that is compatible with your type of fuel. Some gasoline fuel stabilizers do not work for diesel engines and vice versa. Some fuel stabilizers work better with ethanol blends. Make sure you get the correct type of fuel stabilizer for your engine and fuel type.
Cleaning and Lubricating Properties
A fuel stabilizer's primary function is to keep your gas fresh for a period of time. Cleaning and lubricating your fuel system is a secondary consideration, which is why some fuel stabilizers do not contain those additional additives. Many stabilizers offer both benefits but it’s important to confirm the one you’re buying will fit all of your needs.
Formula
Gasoline storage during the winter comes with its own set of challenges. If you primarily store your vehicles and other gas-powered devices during the winter months, make sure you use a fuel stabilizer formulated for that purpose.
Another formula consideration is water absorption. One of the key ways fuel degrades over time is by absorbing water. This is one reason ethanol blend gasoline degrades faster than non-ethanol and why some states reduce the ethanol content during the winter months. If a fuel stabilizer contains alcohol it will compound this problem and fail to adequately protect your fuel.
FAQs
You’ve got questions. The Drive has answers.
Q: Do fuel stabilizers really work?
A: Most fuels start to break down in as little as three months. Chemical reactions plus the evaporation of some volatile components reduce the fuel’s ignition properties leading to contaminated fuel systems and poor engine performance. Fuel stabilizers prevent the fuel from breaking down, keeping it fresh for up to two years.
Q: Can you put too much stabilizer in gas?
A: It’s possible to put too much stabilizer in gas, but unlikely. STA-BIL states that you can safely use up to four times the normal dosage of one ounce of fuel stabilizer per 2.5 gallons of gas. So an eight-ounce bottle of STA-BIL will safely work on as little as five gallons of gas.
Q: Can the fuel stabilizer hurt your engine?
A: Fuel stabilizers are essential for preserving gasoline and diesel fuel which break down in a short period of time. These products do not hurt your engine and help prevent engine failures as well as prevent your engine from failing to start after a long period of storage.
Q: How long does it take for gas to go bad?
A: Regular gasoline has a shelf life of 3-6 months, while diesel can last up to a year. Ethanol fuel blends have the shortest shelf life, losing combustibility in just one to three months due to oxidation, evaporation, and water contamination.
Q: What happens if you don’t use fuel stabilizer?
A: If you don’t use a fuel stabilizer it could lead to poor performance or an engine that fails to start after several months of storage. Left for a longer period of time, the fuel could gum up or corrode the fuel system, leading to extensive and expensive repairs.
