Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (2023)

For any boater who has had the privilege of enjoying the perfect blend of engine and fuel additive, without the latter would almost always mean less than optimal tuning. It's like spaghetti and meatballs or mac and cheese. Can we really blame them for the way ethanol and carbon from most fuel products wreak havoc on engines?

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (1)

This rings true even for those looking for something more specific, like the best fuel additive for 4-stroke outboards. With the correct setup, you'll be able to see the big difference it makes in your engine's fuel efficiency, preventative maintenance, and overall performance.

In case you happen to be looking for the same combination that is right for the money, reading my review of the top rated fuel additives might be all you need to do.

Top 1

Sea foam SF-16

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (2)

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (3)

+ Easy to use
+ Takes care of rough idle
+ Improves overall engine performance

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Top 2

STA-BIL 360 22240

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (4)

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (5)

+ Slightly increases fuel consumption
+ It helps in the smooth operation of the engine
+ Consistent problems with ethanol like corrosion

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first 3

YAMAHA fuel additive

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (6)

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (7)

+ Great value for money
+ Well recognized brand
+ Significantly improves performance

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  • Top 10 Fuel Additives for 4-Stroke Outboards
    • 1. Engine treatment with marine foam SF-16
    • 2. STA-BIL 360 22240 Marine fuel stabilizer
    • 3. YAMAHA ACC-RNGFR-PL-12 gorivo additives
    • 4. Star Brite 14308 Star Tron Enzyme Fuel Treatment
    • 5. Yamaha ACC-RNGFR-PL-32 Outboard fuel additive
    • 6. Merkur 8M0047920 Quickare fuel treatment additive
    • 7. Star Brite Star Tron Enzyme Fuel Treatment Concentrate
    • 8. Mercury 8M0047931 Marine Quickleen
    • 9. Quicksilver 858080Q03 Power Tune
    • 10. LUCAS LUC10013 Fuel treatment
  • Driver for buyers
  • What is a 4 stroke outboard fuel additive
  • Is meerschaum safe for 4 stroke outboards
  • Which is better seafoam or STA-BIL
  • Conclusion

Top 10 Fuel Additives for 4-Stroke Outboards

1. Engine treatment with marine foam SF-16

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (8)

A true classic, the no-nonsense use, performance and guaranteed results of Sea Foam make it one of the safest options for sailors.

This product served as my sweet introduction to the wonders of fuel additives. Then I was intrigued by the brand's claim that you just need to add it to your gas or diesel fuel. It's basically a pour-and-go setup.

It's safe to say that I got more than I expected. I have seen the huge difference it has made on my already fuel efficient Yamaha outboard. This 4 stroke outboard gas has further increased my fishing boat's MPG by as much as 3 miles to be exact. As a regular angler, this is always a welcome bonus for me. This oil treatment allows me to cover longer distances and brings with me numerous benefits.

I also noticed that it took care of the occasional rough idle that I used to experience. I admit it's a pretty old engine, 4 years already. Even so, I bet it was more of a dirty fuel injector problem and this product fixed it after the first tune up and cleaning. I made sure to add it with every full tank to improve performance.

My only real gripe is that it is a bit more expensive compared to other products. I can empty a whole 16 oz. in one attempt. Based on my boating habits, it can be quite a drain on the wallet in the long run.


  • Easy to use
  • Consistently delivers fuel efficiency results
  • Takes care of the rough idle
  • Improves overall engine performance


  • More expensive than most

If you don't want to go through all the trouble of fixing a 4-stroke engine problem, taking the ever-reliable Sea Foam marine pro additive is a guaranteed choice. It saves you the time and hassle of looking for the right solution.

(Video) Top 10 Best Fuel Additives Review in 2023

2. STA-BIL 360 22240 Marine fuel stabilizer

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (9)

The right outboard fuel additives should be easy to use as they can provide all the benefitsfuel stabilizers. If I could name one good example of a product that deserves that label, the STA-BIL 360 marine is often the first that comes to mind.

I cannot completely avoid ethanol fuel products for my boat, with the vast amount of these products on the market. The good thing is that there are ready-made solutions for the said problem, and this fuel stabilizer basically solves it directly. For the amount of expensive damage ethanol can do to my boat's outboard motor, this is practically the more economical, long-term route.

It also kills two birds with one stone as local, extreme weather in the southeastern US where I live can also contribute to the damage. I have been using the one gallon version of this product for quite some time now and I have yet to see any signs of corrosion.

Maybe I'm used to it by now, but I can safely say that my charter boat's 4-stroke engine runs cleaner and quieter compared to other boats I've ridden. In addition to the smoother performance, I also get more gas mileage, although it's only a subtle difference (about 2 miles more) based on the little test I did. Even so, this convenience is one of the main reasons why I can no longer live without great outboard fuel additives.

My complaint about this additive, especially the one gallon variety that I buy often, is very minor. It doesn't use the easier-to-pour squeeze container that other choices have.


  • Great for boats with ongoing ethanol issues like corrosion
  • Slightly increases fuel consumption
  • Actively maintains the quality of fuel and marine engines
  • It helps in the smooth running of the engine

For thoroughtreatment with ethanol for breadand incredible efficiency gains, you'll be hard-pressed to find a product that delivers such quality and honest results as this one.

3. YAMAHA ACC-RNGFR-PL-12 gorivo additives

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (10)

This Yamaha concoction is a powerful cure for the ills of a 4-stroke outboard, and can revive it like a strong caffeine boost in the morning—only it lasts longer.

I purchased this fuel additive after my 9 year old 30hp Yamaha outboard started showing signs of sputtering. It took almost three visits to my local garage before I realized that I shouldn't have been too eager to follow every mechanic's advice. I browsed the net for a few days after the problem remained unresolved, and long story short, that trip led me to this product after several recommendations.

I was drawn to the fact that it was made specifically for 4-stroke engines. Ultimately, I will always give him credit for solving the idling problem that my boat's engine and I had been suffering for almost a month. I'm more than willing to shower praise on products that need time to flesh out their capabilities and, more importantly, deliver what they promise. Minemarine enginenever sounded this smooth in a long time.

I also noticed a significant improvement in my bowl speed after the first few bottles. Unfortunately, I can't say much about the supposed protective abilities it has since I've only been using it for 3 months. However, since we are talking about such an established brand as Yamaha, I am confident that it is doing a good job in this regard as well.

For this reason, it is expensive, which I definitely hate. But for what I got, I can say that it provides excellent value for money. Plus, I paid a lot more for those back-to-back trips to the mechanic, even though I got nothing out of it in the end!


  • Specially formulated for 4-stroke engines
  • Solves a common outboard motor problem
  • Significantly improves performance
  • A well-recognized brand
  • Great value for money


  • Expensive

Like a powerful elixir, I know I can always rely on this fuel additive when my marine engine starts coughing and showing other signs.

4. Star Brite 14308 Star Tron Enzyme Fuel Treatment

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (11)

Cost-effective and more affordable, Star Tron's additive is a must-have for anyone looking to get the most out of their fuel and hard-earned cash.

This basically consumes the ethanol that may be present in the gas you are using. Of course, that's a good thing because my marine fuel went bad after only two weeks, so it didn't damage the engine. You can only imagine the money I save by relying on this neat fuel treatment, which extends the life of my fuel up to 2 years.

I have found that it works well with meerschaum, especially when maintaining the quality of the gasoline for my boat. Even when I leave the boat idle for a few months, it immediately starts on the first crank as if I had only used it yesterday. I attribute the longer fuel life mostly to my decision to combine it with the sea foam as I don't get the same longevity when using either one alone.

I also use this to replenish old, extra fuel that I usually store when I don't have as much time for fishing and boating. I even found it ideal for my lawnmower and chainsaw. More importantly, I can confirm that it works best for my boat's small 4-stroke engine, as evidenced by the stable performance I get every time.

I hope the brand will consider including a way to measure the amount I pour as I tend to be meticulous with my mixes.


  • Effectively solves problems with ethanol
  • Works well with sea foam
  • Affordable and allows you to save more fuel in the long run
  • Optimal engine protection
  • Versatile use


  • Can use meter
(Video) Top 10 Best Fuel Additive (2023)

While I won't name them directly, I feel that this product is a far better option than several of the additives listed here, especially if I crunch the numbers.

5. Yamaha ACC-RNGFR-PL-32 Outboard fuel additive

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (12)

For anyone with a 2-stroke or 4-stroke outboard from this brand, look no further than Ring Free. It's their power juice.

I thought the only logical thing to do was to buy this for my 5 year old Yamaha outboard when it started showing signs of hesitation issues. Admittedly, I wasn't a fan of the price, and this is coming from someone who typically exceeds 70 hours of active sailing time each season. It's a once or twice a summer purchase though, so no big deal.

Going back to the problems it solved, it has pretty much solved all the ethanol problems I've run into suddenly when the usual signs show up. I usually go the shock treatment route and pair it with seafoam when I use this mix, and it always gives good results. The engine started to run quietly and the air grills and filters stayed clean and worked like rain.

Idling at low speeds has become smoother. I have also found that I no longer need to change the spark plugs, even if I shock the engine as long as I use this seafoam additive. By the way, I also recommended this additive to my fishing friend who happens to have a 15 year old motor, and he got mostly the same results.

I wouldn't mind the price if I don't fish or sail as often as any regular boater. Despite this, I can safely say that I get my money's worth with every purchase.


  • Specially created for outboard motors
  • Keeps filters and air filter clean and in top shape
  • It can be used to restore the performance of old Yamaha engines
  • Works well with sea foam to keep spark plugs clean
  • Great value for money


  • Expensive for frequent sailors

This Yamaha outboard fuel additive is special in many ways, as proven by its benefits. Once you try it, you'll see the wonders it brings to this type of engine with that brand name.

6. Merkur 8M0047920 Quickare fuel treatment additive

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (13)

Anyone with a Mercury outboard should listen to the dealer's recommendations and opt for Quickare's timely solutions to most ethanol-induced outboard problems.

The primary strength of this fuel additive lies in its uniqueness in its brand. It may not be as versatile as other options like sea foam, but I wouldn't trade it for any other treatment if I had this brand of outboard. Almost every applicable boat I've used this on, either mine or owned by someone I know, solves all the common ethanol and deposit problems.

I always appreciate a safer option that meets the manufacturer's recommendations for the additives I use for the 4-stroke outboards. I'm glad I won't have to have that dilemma when I need it for anything made by this brand. I get smooth performance from my outboard and a sound that is just music to the ears of any consummate boater.

I haven't tried it on other brands of outboards, but I have a friend who can confirm that it works better than STA-BIL. This is also proven by some feedback on Amazon.

I have to criticize the relatively shorter duration of its ability to keep the fuel fresh. I like that the brand is transparent when it states that it keeps fuel up to 3 months. However, that's too short a time compared to other plugins I've used.


  • Excellent at solving ethanol and scale problems in Mercury outboards
  • Meets the manufacturer's recommendations
  • Ensures smoother engine performance with better sound
  • Works better than STA-BIL according to feedback from several users


  • The stabilizing effect is not as long as other fuel additives

This brand-focused additive is as solid as most of the great products on this list when it comes to delivering the desired effects.

7. Star Brite Star Tron Enzyme Fuel Treatment Concentrate

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (14)

Any boater who has perennial problems with ethanol gasoline, among which are not only expensive engine repairs and short fuel life, should know that he can find a reliable partner with this additive. It provides a host of benefits rarely enjoyed by boaters who rely on fuel additives.

For one thing, I rarely get at least two to three years of extended ethanol and gasoline life every time I put it in my fishing boat's 4-stroke outboard. I even use it for all other vehicles with small engines, especially if I have no choice but to use ethanol. I have been using it for almost three years on my boat and have yet to notice any damage to the entire fuel system.

I like that it saves me the hassle of regularly cleaning the carburetor. Any time saved as a direct result of the product's effects is gold to me. Moreover, I hardly have to pull more than once to keep the engine running like new as long as I use this additive.

I think it is important for the brand to start paying attention to the design of the bottle. I completely agree with other users who complain about the amount of spillage almost every time I try to pour this product out of its one gallon container.

That's a big no-no, given the fact that I tend to pay higher prices than more established brands. The bottle issue is unfortunate because I consider this product to be a solid alternative to them. I'm just comforted that I can always rely on the syringe for more accurate measurements.


  • Proven to retain ethanol gasoline for up to 2 to 3 years
  • Cost-effective and saves effort for a long time
  • It helps to start the engine quickly
  • Works with most small engines


  • Difficult to pour without spilling
  • A bit more expensive
(Video) Top 10 Best Boat Fuel Stabilizers Review in 2023

Despite its flaws, I won't be willing to trade this outboard gas additive for anything that can't outweigh its strengths.

8. Mercury 8M0047931 Marine Quickleen

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (15)

Mercury's Quickleen proves the point that it is infinitely better and safer to opt for specialized formulations made for marine engines in most cases.

I used to use a number of fuel additives and stabilizers for my 4 stroke outboards. However, few products are as reliable and adaptable to specific vessel problems as this formulation can solve. I still use it for most of my outboards, 2-strokes and 4-strokes of various horsepower, and let's just say it has saved me numerous trips to the mechanic.

I have used this to solve my hesitation and misfire problems. Even when I wasn't very knowledgeable about cleaning injectors, I remember just pouring this into one of my speedboat's 100hp 4-stroke outboards and it solved the problem in no time. I would definitely use this first before committing to any permanent changes like replacing the plug and coil to save myself unnecessary expense.

In most cases, I've found that you just need to be patient to see results, especially if you want a pick-and-span fuel system. I've tried it on Yamaha and Mercury outboards and got the same benefits as any other fuel stabilizer, if not more in terms of money saving benefits.

Can't say much about the brand's claim of extending spark plug life. However, I can confirm that I rarely have to replace it unless I shock the engines, which is not very common.

Although it is affordable compared to other products, I feel it pales in comparison to other brands when they are other brands. This is because I almost always need to leave as little fuel in the tank as possible to get the most out of the benefits of fuel retention.


  • Works well for Yamaha and Mercury outboards
  • It solves a number of problems associated with the outboard motor
  • It helps you save more money on repairs and replacements
  • More budget friendly


  • Doesn't hold fuel as well as other brands

If your primary concern is getting an additive that will solve a problem associated with a 4-stroke engine, or if you are looking for specificity, then I highly recommend this product.

9. Quicksilver 858080Q03 Power Tune

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (16)

This neat spray could magically solve any carbon-related ailment your outboard might be experiencing. A good dose is often enough to get my engines back in top condition.

This product saves me from relying on the usual shock treatments to remove any excess carbon in the carburetor of my Evinrude outboard. I love that I really only need to spray it on the carburetor to get the job done. Of course, I still need to use up all the old fuel, but it almost always makes a big difference in starting the engine and running later.

This has since become my go-to carburetor cleaner for my 4-stroke outboards. Where others have failed to remove all that stale, old gas, this one proved to be the exception. The moment I sprayed it for the first time and those trademark foams appeared, I knew I had made a wise choice. Almost any part of your fuel system with carbon buildup will benefit from this powerful spray.

The opposite only means expensive disassembly, which I'm glad I can postpone or avoid with the help of this product. It not only saves money, but also a lot of time and effort. Sometimes I even just soak one of my engine's carburetors with this solution overnight and get the same results.

It also has a decent price. I have no major criticisms of it, except that it could be better packaged. After all, my last order arrived with a broken nozzle.


  • Specially formulated for 4-stroke gasoline engines
  • Easy to use thanks to the spray design
  • Excellent carburetor cleaner and decarbonizer in general
  • It saves time and effort and costs more in the future


  • Sometimes poorly packaged

I wasn't kidding when I said this product works almost like magic when it works as an outboard cleaner. Choose this if you need a quick carburetor cleaning.

(Video) Best Fuel Injector Cleaner 🔥 Top 5 Best Fuel Injector Cleaner Reviews

10. LUCAS LUC10013 Fuel treatment

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (17)

I use this product as a fuel treatment when I want to save money to improve the performance of my outboard and get the most out of my fuel. Profitability is written everywhere.

Considering the cost of a gallon of fuel additives on the market today, this LUCAS fuel treatment is a godsend. That's almost guaranteed performance gains and long-term fuel savings for less money. I travel 50 to 70 miles while cruising and based on my tests I get a slight but no less significant increase of no more than 2 MPG with my boat.

It doesn't matter that I can use it for my trailers as well. I no longer go without this product because of the way my outboard runs smoother and quieter. I can always hear the difference when I use this and when I don't, and I can say the same for my trailers.

I even remember one time I was riding in one of my friend's boats and the engine sputtered. It's a good thing we brought my trailer where I keep a supply of this excellent additive. Long story short, we added this stabilizer to the outboard before we filled it with fresh gas, and after about two miles of coughing the engine up, the problem went away completely.

Through these benefits alone, I can confidently state that I'm already getting my money's worth every time I buy another gallon of this product. I do wish it was easier to know how much cleaner goes into the container though, and they could have just added measuring tools to the large bottle. Moreover, the design of the bottle makes it difficult to pour directly.


  • Cheaper than others
  • Proven to slightly increase fuel consumption
  • Versatile, it can support many types of vehicles
  • Quickly solves engine splash problems
  • Excellent value for money


  • An accurate meter is required
  • The design of the bottle makes pouring difficult

Many drivers and boaters find it hard to turn down this product because of the cost savings and benefits it brings. I can proudly say that I am one of them.

Driver for buyers

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (18)

Your purpose for using the additive on your boat's 4-stroke outboard should be one of the main considerations when deciding on the best type of product. Do you want to solve the problems commonly associated with ethanol in fuel? Or just want your gas to last longer and improve engine performance? Maybe you want to decarbonize your boat?

As my review of fuel treatments, cleaners and additives can attest, these products do not have the same benefits, at least in certain cases.

Some choose to specialize in marine engines, while others are more versatile and can service a number of vehicle types and engine sizes.

It's safe to say that you should keep these exact benefits in mind and know if they apply to your exact situation or meet your specific needs. In addition to this important factor, it will not hurt to look at these areas:

Fuel and engine compatibility

Double check that the additive matches the brand of your 4-stroke outboard (eg Yamaha outboard additives) and the type of fuel you use with it. Each product should tell you which species it works best with. If this information is not readily available, be sure to check with the manufacturer.

Ease of use

Practicality should not be neglected. Does the product require you to take extra, complicated steps just to reap its benefits? How is the bottle designed? Does it help you take accurate measurements so you can pour a precise measure with every gallon of fuel in the blink of an eye?

Duration of stabilization

If you want your fuel to stay viable for as long as you want, you need to know the products that can deliver. Of course, you should also take into account any seasonal changes that might affect this. Winter may make some stabilizers less effective, at least compared to their winter-formulated counterparts.

What is a 4 stroke outboard fuel additive

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (19)

Sea Foam is the most popular, the safest, and what I would recommend to anyone still trying out fuel additives for this type of engine. More or less, it provides all the great benefits your 4-stroke outboard can get from fuel additives.

However, I can say the same for a few of the other products listed here. Each has its own strengths, especially in the amount of money I save with their help and the engines they work best with. For this reason, I recommend them to everyone.

Is meerschaum safe for 4 stroke outboards

Not only is it very safe, but it is also easy to use and recommended for most 4-stroke outboards. The brand itself confirmed this on its main website. You can always pour directly into the container without any problems. Most boaters use it to quickly repair their boat engines when they have problems with carbon build-up. This is usually achieved by proper shock treatment.

Which is better seafoam or STA-BIL

If I'm going to consider adaptability in the many situations that 4-strokes find themselves in, I'd say the Sea Foam is the winner. The rule of thumb is that meerschaum works better with smaller engines that are more likely to be exposed to moisture, while STA-BIL is the exact opposite.

However, both are household names for a reason. I have found that the STA-BIL is ideal if you plan to keep your boat idle and maintain its fuel for long periods of time, given the wayworks like antifreezewhen it stabilizes its fuel.


I hope with the above information you now have a good idea of ​​what fuel to use in 4 stroke outboards and their ideal additives. To me, the best 4-stroke outboard fuel additive is one that consistently delivers everything you need while helping you save money, time, and effort while driving.

5/5 - (2 votes)

Reviews of the 10 Best 4-Stroke Outboard Fuel Additives for 2023 (20)

Jonathan Larson

(Video) Mercury Marine Recommended Fuel Treatment

I'm passionate about water sports and technical fields, so I'm interested in combining both to create content about boat accessories. My partner and I went on numerous trips and sports games together, which made us think about how we can transfer our joys and passions to many people.


What is the best fuel for a Mercury 4-stroke outboard? ›

Answer: Fuels containing up to 10 percent ethanol are considered acceptable for use in Mercury engines. Fuels containing higher levels of ethanol, such as E15 gasoline, are not considered acceptable for use. The use of fuels containing more than 10 percent ethanol can void the warranty.

Should I run premium gas in my 4-stroke outboard? ›

Current recommendations are to use a minimum of 87 octane, 89 octane is preferred. There is no additional benefit from using higher-octane fuels, in fact they may cause hard starting conditions in hot weather.

Do any fuel additives actually work? ›

Do Fuel Additives Work? Maybe, but it depends on what you're trying to achieve with your fuel additive. They may prevent future car maintenance problems regarding your fuel injectors and buildup. However, fuel additives may not improve your vehicle's fuel economy right away after just one tank.

What is the best fuel additive for gummed up carburetor? ›

We recommend adding B-12 Chemtool Total Fuel System Clean-Up (part #2616) at 1 oz/gal and topping off with fresh gasoline. This additive will thoroughly clean the fuel line, carburetor (internally and externally), intake valve(s), and combustion chamber.

What is the recommended fuel for a 4-stroke outboard? ›

“We recommend 87 octane for both our two- and four-stroke motors. We stress the importance of a good, name-brand gasoline.” Additionally, Grigsby says Yamaha recommends the regular use of fuel additives, such as conditioner, stabilizer, combustion-chamber cleaner and gas-line anti-freeze.

What is the best fuel for 4-stroke engines? ›

The best fuel for 4 cycle engines is ethanol free. Even though ethanol free fuel does not deteriorate carburetors like gas with ethanol, we strongly recommend, running the engine until the tank is out of gas, so only put into the tank the amount of gas you feel you will use.

How many hours will a Mercury 4-stroke outboard last? ›

With proper care and maintenance, many 4-stroke outboard engines can last over 3,000 hours before requiring significant repairs or replacement.

What is the best gas for outboard motors? ›

What Type of Gas Should I Use in My Boat? All current outboard, sterndrive and inboard gasoline engines are designed to operate safely on fuel with no more than 10 percent ethanol (known as E10), and under no circumstance should fuel with more than 10 percent ethanol (such as E15 or E85) be used in a marine engine.

What is the best gas for outboard engines? ›

Our top pick for boats with outboard motors is ethanol-free gasoline. If you go on your boat often and have enough money to invest in it, you should really consider avoiding ethanol. If you don't, there are two low-ethanol options that you can choose between: E10 fuel.

Can you use 91 in a 4 stroke? ›

However, four stroke engines that have fixed ignition timing are designed to run on lower octane petrol such as 91 RON. Using premium 95 RON will cause premature ignition in the combustion chambers, damaging the piston crown/s.

What fuel additive prevents vapor lock? ›

To fight vapor lock, adding a small amount of combustible oil to the fuel (¼ cup to 10 gallons) will reduce the volatility of the fuel; common additives are Marvel Mystery Oil or Diesel Fuel. Adding too much will cause the oil to carbonize during combustion and increase the chance of pre-ignition (knock/ping).

What fuel stabilizer should I use in my boat? ›

VP Marine Fuel Additive – The Best Fuel Stabilizer for Boats

It's a fuel additive that protects your boat and keeps your engines running like new. Ultra Marine is more than a gas stabilizer for boats and other watercraft.

Does seafoam work as a fuel stabilizer? ›

Sea Foam Motor Treatment works to stabilize stored fuel up to 2 years. Adding Sea Foam to stored tanks helps fuel resist evaporation, preserves ignition vapors, adds protective lubricity, and prevents the formation of gum and varnish in fuel systems.

Can fuel additives cause problems? ›

The good thing is that, even if you use the wrong additive, it probably won't harm your engine. These additives are designed to solve specific problems without causing other ones. This no-harm design means that, in general, you can safely use an additive without worrying about doing damage to your engine or fuel.

Can you overuse fuel additives? ›

You can easily add too much of a high-quality diesel fuel additive. What happens when you over-treat your diesel fuel? Overdosing can lead to a whole new list of fuel and engine issues from clogged filters to overall decreased engine performance and efficiency. If you're losing lubricity, don't over-treat.

Is Sea Foam a good fuel injector cleaner? ›

It works through fuel injectors and carburetors to remove harmful residues and deposits from fuel passageways, intake valves, pistons, and chamber areas. Made from petroleum ingredients, Sea Foam is safe and effective when used in all types of gasoline or diesel fuels and fuel blends.

Is seafoam bad for carburetors? ›

Use Sea Foam Spray to safely and effectively clean residues and deposits from intake valves, chambers and compression rings! Sea Foam Spray delivers a high concentration of petroleum cleaning solvency and lubricity to carburetor throttle valves, intake runners and valves, and chamber areas.

Will seafoam clean a gummed up carburetor? ›

After removing gasoline from the tank and carburetor, add a mixture of Sea Foam followed by 8 ounces of fresh gasoline (1 to 2 ratio). 5. With the cleaning mixture in the fuel tank, crank/prime/rope-pull the engine to draw the cleaning mix into the carburetor(s). 6.

Do 4-stroke outboards need special oil? ›

Use a motor oil specifically formulated for the rigors of the marine environment, like Yamalube® 4M for 4-stroke outboards, and Yamalube® 2M for two-stroke outboards. Marine engine oils are so different in their requirements that special levels of certification exist: FC-W® (4 stroke) and TC-W3® (2 stroke).

What octane rating do typical 4-stroke small engines prefer? ›

A minimum of 87 octane/87 Anti-Knock Index (AKI) / 91 Research Octane Number (RON); If operating at high altitude, see below. Gasoline with up to 10% ethanol (gasohol) or up to 15% methyl tertiary butyl ether (MTBE), is acceptable.

How much more fuel efficient is a 4-stroke outboard? ›

4-Stroke Outboards Pros

The fuel efficiency of a 4-stroke motor can be 50% better than that of a 2-stroke motor with the same HP. As for environmental concerns, 4 stroke outboards produce far less harmful emissions, which can be as much as 90% cleaner than those from a similar sized 2-stroke motor.

What fuel is best for horsepower? ›

Premium gas has a higher resistance to engine knock in luxury and performance vehicles with turbochargers or high-compression engines, so you can hit that horsepower smoothly. Additionally, premium gas can increase fuel efficiency, potentially bringing better gas mileage for longer while decreasing emissions.

Which is the most preferred as a engine fuel? ›

engines fuel most preferred are paraffins and for S.I. engines fuel most preferred are aromatics.

What type of fuel injection is best? ›

The sequential fuel injection is the most effective and efficient of all the fuel injections systems currently available in the automotive industry.

How often should you service a Mercury 4-stroke outboard? ›

The maintenance schedule for the Mercury 150 FourStroke, and for most four-stroke outboards, calls for changing the oil and the oil filter every 100 hours, or annually. For many boat owners this annual oil change is part of preparing the outboard off-season storage.

What is the top speed of a Mercury 4 hp outboard? ›

Performance Table
Minimum3.3 knots
Medium7.5 knots
Max12 knots (15 knots with one single person on board)
May 3, 2019

How many hours does it take to break-in a new Mercury outboard? ›

Once the hour meter hits the 10-hour mark, the break-in process is complete and you are free to run the engine as you normally would.

What brand of outboard is most fuel efficient? ›

Suzuki DF90A - Best All-Around Mid-Size Outboard

A smaller, lighter, more fuel-efficient home-run hit.

Should I run my outboard out of gas? ›

There is no harm in running your motor out of fuel with four strokes engines, but it's not necessary to do in most cases (again, refer to your owners manual).

How long can gas sit in boat? ›

Boat fuel can go stale within 30 days, especially if it's mixed with ethanol, as it is in some areas. Stale fuel will degrade and can clog the fuel system. You can extend the life of the fuel by topping it up with some fresh fuel.

What is the difference between seafoam and seafoam Marine Pro? ›

Both products are similar, but Marine PRO is the best treatment you can use in a marine engine. It's specially formulated to help prevent and overcome the issues that marine engine owners deal with the most – like hard starting, rough idle, fuel degradation, premature engine wear, and corrosion.

What grade of gas is best for a boat? ›

Gas Powered Boating

Depending on the engine make, model or size, the type of fuel required may vary. For many newer recreational boats today, an ethanol-free 87, 89, or 91 octane will do the trick. If you've got access to an on-water gas station, you can count on the fact that they will have what your boat needs.

Is 93 octane OK for boats? ›

AdamCord. All of the later model boats have high compression engines that were designed to run on 93 octane (US Octane) fuel. They all have the ability to run on 87 but that does NOT mean you are getting the best out of your boat.

What happens if I put 89 instead of 91? ›

If you put lower-octane fuel into your high-octane vehicle, whether by mistake or to save money on gas, you'll probably notice the effects right away: things like poor fuel economy, reduced acceleration, and spark knock, which sounds like a high-pitched pinging or rattling noise.

Which gas brand is the best? ›

Chevron. Of America's largest nationwide chains, Chevron scores the highest points in overall customer satisfaction. Its reach spans over 7,800 stores, and while some gas stations offer convenient food marts, one location in North Hollywood goes above and beyond gasoline.

What happens if you put 93 in a 91? ›

“If the octane is less than 91, the engine could be damaged and the repairs would not be covered by the vehicle warranty. If heavy knocking is heard when using gasoline rated at 93 octane, the engine needs service," the owners manual reads.

At what temperature does gasoline vapor lock? ›

For summertime operation, the fuel is blended to offer multiple boiling points, with a small portion designed to boil at “low” temperatures of 70 degrees, while the more stable ends will boil at a much higher temperature, perhaps 150 to 175 degrees.

Does ethanol gas cause vapor lock? ›

Adding 10% of Ethanol to Gasoline – as is currently done in the USA - drastically reduces the V/L ratio temperature. Therefore a critical vapor liquid ratio, which can cause vapor lock, will be reached at lower temperatures with Gasoline-Ethanol blends than with regular Gasoline.

How do you reduce vapor lock? ›

If you're wondering how to prevent vapor lock, try using a thermal barrier like a heat shield, or heat sleeve. Whether you have a carburetor or use fuel-injection in your vehicle, vapor lock can bring your vehicle to a standstill causing hours of frustration.

What is the best fuel for a Mercury 4 stroke outboard? ›

Answer: Fuels containing up to 10 percent ethanol are considered acceptable for use in Mercury engines. Fuels containing higher levels of ethanol, such as E15 gasoline, are not considered acceptable for use. The use of fuels containing more than 10 percent ethanol can void the warranty.

What happens if you use too much Stabil? ›

WILL OVER-DOSAGE CAUSE ANY HARM? No, over-dosage is perfectly OK. However, we do not recommend adding more than 4 times the recommended amount.

Can you put too much Sea Foam in your gas tank? ›

It can't harm engine parts or components. You don't have to worry about messing anything up by adding “too much.” The more Sea Foam Motor Treatment you add to fuel, the better it cleans (up to a point, of course). At a minimum, add 1 ounce of Sea Foam per gallon of fuel.

Do you add Sea Foam to gas or oil? ›

Added to oil, Sea Foam liquefies heavier petroleum residues and deposits back into the fluid so everything drains away when it's time to replace oil and filter. Pour it in every oil-change interval to keep oil flow passageways cleaner and help the engine last longer!

Is fuel system treatment worth it? ›

A clean fuel system can improve the longevity of your vehicle, increase power and performance, improve fuel economy and drive ability. Many of us tend to neglect cleaning our vehicle's fuel system, not realizing that this is actually a vital component to prolong the life of your car.

Is fuel additive cleaner worth it? ›

Is it worth adding to your gas tank? In short, when used regularly, fuel cleaners work. They can help remove harmful deposits, prevent new deposits from forming, and enhance vehicle performance. Fuel additives can improve gas mileage, reduce long-term maintenance costs, and they're affordable.

What is the difference between gas treatment and octane booster? ›

Octane boosters are designed primarily to boost fuel octane levels, whereas fuel stabilizers are designed primarily to extend the life of fuel. If you're planning to store your vehicle for an extended period, such as the current season, you may want to use a fuel stabilizer.

Is fuel injector cleaner better than fuel system? ›

Do you want a fuel system cleaner or a fuel injector cleaner? Again, fuel system cleaners are typically stronger since they need to clean all parts of the system, but fuel injector cleaners are usually cheaper.

Which is better gas treatment or fuel injector cleaner? ›

Fuel injector cleaners typically have a superior cleansing strength and last longer between applications when compared to gas treatments. Injector cleaners are added to the fuel tank at oil changes.

What is the best fuel treatment for gas engines? ›

  • #1 Editor's Choice: Lucas Upper Cylinder Lubricant & Fuel Injector Cleaner. ...
  • #2 Best Fuel System Cleaner: Chevron Techron Concentrate Plus. ...
  • #3 Best Value: STP Fuel Injector & Carburetor Cleaner. ...
  • #4 Best For Clogs: Red Line 60103 Complete SI-1 Fuel System Cleaner. ...
  • #5 Also Consider: Royal Purple 18000 Max Atomizer.
Feb 19, 2023

Which fuel system is best? ›

Direct Injection

This system is the best in class, primarily used in diesel engines. It's much more expensive and complicated to set up in petrol cars. In Direct Injection, the fuel goes directly to the cylinders past the valves, allowing more control over the engine and measuring out the fuel with better precision.

Which fuel injector cleaner is better? ›

1. Best Fuel Injector Cleaner for Smoother Idling—Sea Foam IC5 Fuel Injector Cleaner. Sea Foam's fuel injection cleaner filters through to clean out the whole system and boost fuel efficiency, but it also gives a little lubrication to upper cylinders.

What fuel additive has the most pea? ›

Gumout High Mileage is formulated with one of the highest concentrations of PEA on the market to attack large caked-on deposits. Don't be surprised if that takes repeated uses, which is why Gumout makes their cleaner available in a six-pack of six-ounce bottles.

Does it matter what fuel cleaner I use? ›

Buying a high-quality cleaner

If you buy a cheap fuel injector cleaner, it most likely won't have the proper detergent package to do the job. If you get a high-quality fuel system cleaner (i.e., higher quality and quantity of detergent), it will clean up these deposits in the entire fuel delivery system.

Is seafoam a good fuel injector cleaner? ›

It works through fuel injectors and carburetors to remove harmful residues and deposits from fuel passageways, intake valves, pistons, and chamber areas. Made from petroleum ingredients, Sea Foam is safe and effective when used in all types of gasoline or diesel fuels and fuel blends.

Do I need fuel injector cleaner if I use top tier gas? ›

Top Tier fuels, like Sunoco Ultratech, led to a lower likelihood of deposits building up in the first place, so there are no deposits there to need cleaning. They also work harder to clean and then prevent deposits from forming on the tips of the fuel injectors.

What are the disadvantages of octane boosters? ›

“Octane boosters can cause damage. An example would be operating an automobile engine using aviation fuel. Aviation fuel is higher octane and contains lead. Leaded fuel will damage the catalytic converter and sensors.

Why is Lucas octane booster not street legal? ›

Lucas Octane Booster is safe for use in any engine on the track or off road. Because of its high potency, this product is not street legal. This product can expose you to naphthalene, which is known to the State of California to cause cancer. For more information go to

What happens if you put too much octane booster? ›

In what ways can octane booster harm an engine? If alcohol is being used to boost octane, too much alcohol will cause an engine run lean. If MMT is being used too much will cause oxygen sensors and catalytic converters to fail. It will leave the inside of cylinders and plugs orange.


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