The Ultimate Guide to Fuel Additives

Car owners can utilise many things to make their vehicles perform better. Be that modifications that provide enhanced power, tools and techniques to increase your mileage or additional substances that you can add to your vehicle; you have many options as a car owner. 

With cars being expensive purchases, it makes sense to have the quality and health of your car be a priority. This is why so many of these types of products are becoming popular. 

Fuel additives are one product that’s really influential in keeping your car in excellent condition. These are solutions that you put into your fuel tank to protect your engine and fuel system while also making your car perform better. 

If you’re interested in including fuel additives in your maintenance routine, Car Adviser has put together a complete guide to help you learn more about this product.

In this guide

What are fuel additives?

A fuel additive is a compound created to improve the performance and efficiency of the fuel that’s used in cars and various other vehicles. 

They can either increase a fuel’s octane rating, act as lubricants so that there’s less corrosion within the fuel system, making the car work more efficiently while generating better power, or combine these benefits in one product.

The octane rating for fuel measures its ability to withstand compression when in a combustion engine without detonating. In other words, it measures its stability. A higher octane rating makes the fuel safer and less likely to combust, which also has the added benefit of making it perform much better. 

A fuel additive will make a car use the fuel more efficiently. This means you should get a few more miles per gallon, resulting in less frequent refills, which could help you save money. There will also be fewer carbon deposits left behind once the fuel has burned, meaning that more of the fuel is being used and that there is far less waste product, making your car much better for the environment. 

Not only can it make your car more efficient and stable, but because there are fewer carbon deposits within your fuel system, you’ll also notice a boost in performance. Things like acceleration will be more responsive because the components will be much cleaner. Because of their benefits, we recommend that all drivers start to use fuel additives. 

How to use fuel additives?

When using a fuel additive, it’s always best to add it to your fuel tank before you fill it up with your required fuel. This is because these types of treatments work best before there is combustion. Also, ensure that the tank is completely empty before adding the fuel additive to work more effectively. 

They aren’t something you add to your fuel each time you fill up at a petrol station. Instead, it’s best to use a fuel additive every 3,000 – 5,000 miles of driving, meaning that they’re something that you use pretty infrequently.

For fuel additives to work best, they need to be mixed with premium fuel, meaning these only work best if you’re willing to spend a bit more on your car. 

You should also use the recommended amount of fuel additive for each treatment and not be tempted to use more. This is because adding too much can cause your filters to get clogged, which can impact the efficiency and performance of your vehicle. 

Each manufacturer will have instructions on how much fuel additive you should use each time. This amount may differ depending on the brand, so read these instructions before you begin your treatment. 

What are the different types of fuel additives?

There are multiple types of fuel additives, all focused on delivering a slightly different solution. For example, some focus on keeping your fuel system clean and clear of debris, while others are designed to make your fuel perform better. 

To help you pick the best type of fuel additive for you and your vehicle, you must first decide what overarching goal you want to achieve. Once you determine what you wish to improve on your car, you can use any of the following fuel additives. 

Do note that you shouldn’t mix different types of additives in an attempt to get all their benefits. This can overload your fuel tank and cause issues, especially if the solutions react. 

Some of the most common types of fuel additives include: 

Gas Treatments 

These types of fuel additives are the most common and cheapest to buy. They’re formulated with polyisobutene, a variety of synthetic rubber, and are designed to eliminate carbon deposits that can be left behind in your fuel system. 

Removing these deposits improves the quality of your fuel, helping you create cleaner emissions while also breaking down water particles so that the fuel doesn’t dilate. 

Using gas treatment fuel additives to improve your emissions can help you become more environmentally friendly and potentially help you save money on road tax. This is because you may have to pay less due to your reduced emissions. 

Fuel Injector Cleaner

These types of fuel additives are an enhanced version of the simple and cheaper gas treatments. This is because instead of polyisobutene, they contain polyetheramine (PEA), considered one of the strongest cleaning agents available. 

With this enhanced substance working away, you’ll be able to clean far more parts within your car, including the direct fuel injectors. This can make your car function a lot better, making it more powerful and economical. This compound can also remove clogs and carbon buildup in the fuel filter, helping that component to work really well.

Fuel Stabiliser

The fuel in your car diminishes in quality over time, especially if it’s left in storage for a long time or if your car has been idling for a while. This reduction in quality makes it much less economical and can also significantly impact your car’s power and responsiveness when accelerating. 

Fuel stabilisers combat this problem by maintaining the quality of the fuel so that it’s in excellent condition for longer. It works by absorbing any water in the fuel so that it’s not diluted, and it also inhibits the oxidation and chemical breakdown that naturally happens within the fuel. This means that it can last a much longer time with a fuel stabiliser.

Octane Booster 

An octane booster is a type of fuel additive that isn’t as concerned with cleaning your fuel system and instead is designed to increase the octane level in your fuel. The octane level is significant, as a higher level correlates with better fuel efficiency and performance. With an octane booster working to improve your octane level, you’ll produce far fewer emissions and greenhouse gases.  

As well as increasing the octane count in your fuel, this additive can also help clear away carbon deposits from the fuel intake system. Octane boosters are usually added to the gas tank before you fill it up with fuel.

What to consider when buying fuel additives?

There are a lot of things that you need to think about when buying the best fuel additive for you. Not only do you have to consider what type best suits your needs, but many other factors determine how good a fuel additive is and how suitable it is for your car. 

Here are a few things you should consider when shopping for your first fuel additive. 

Engine Compatibility

Like how some cars take either diesel or petrol, some fuel additives only work with specific vehicles with a particular fuel type. For example, you can find fuel additives that only work with petrol cars. It’s essential that when shopping for fuel additives, you don’t make the mistake of buying one that isn’t compatible with your vehicle. 

Thankfully, some fuel additives work well with both types of fuel. However, their effects may not be as tailor-made and thus not as good as something that’s designed for a specific engine type. 

If you do accidentally buy a fuel additive that doesn’t suit your vehicle, you mustn’t be tempted to use it. This is because adding the wrong fuel additive can cause corrosive chemical reactions, which can damage parts and may cause engine failure.

Repairing an engine failure can be a pretty expensive mechanical job, so to avoid any issues, check your car’s owner manual to know any formulas and ingredients you should avoid. In fact, your owner’s manual is a great way to learn more details about how best to use fuel additives for your specific model. 

Product size

The different sizes of fuel additive bottles come in multiple quantities, which can affect the value for money of each product. For example, you could get a small 11-ounce bottle of fuel additives or massive jars filled with litres of fuel additives. 

Although it may be tempting to get the largest option as it’s likely better value for money, having something that size will likely have to be stored for a long time. This is especially true if you’re not driving your car that often, as fuel additives are only used every 3,000 miles or so. 

No one size’s best for everyone, as one type of bottle will suit different situations. If you only have the one car and don’t need to add fuel additives regularly, a smaller bottle might be more sensible, especially as they’re cheaper to buy. If you have multiple vehicles, a larger option will allow you to treat them all at once. 

EPA Approved

Fuel additives remove carbon from your engine and fuel system. Carbon is a harmful by-product that can pollute the environment, meaning the carbon being dislodged from your car needs to be treated safely and responsibly. 

By getting a fuel additive that has an EPA label, it means that it complies with environmental regulations and that it’s safe to use. It would be best if you prioritised using these types of products over others. 

Ease of Use

Knowing exactly what to do if you’ve never used fuel additives before can be a bit tricky. To make your experience a lot easier, you should consider fuel additives that are easy to use. Find ones that come pre-prepared, meaning that you don’t have to do any mixing, and ones that have clear instructions about how to use it and how much should be used at a time. It’s also wise to find a fuel additive with clear measurements on the bottle, so you know how much of the fluid is left. 

Range of use

Although multiple types of fuel additives focus on different things, it’s best if you only consider the ones with a wide range of benefits. Although all fuel additives will be effective in cleaning your fuel system, the best ones will also be able to lubricate engine parts, keep your fuel stable, prevent corrosion, and work as an engine cooling agent. 

Getting a fuel additive that focuses on this can be the better choice if you’re looking for a specific treatment. However, if you’re looking to get fuel additives to work as a general maintenance step, one that covers many issues will be best. 

Shelf Life 

When getting a fuel additive, especially if you’re going to get a larger container of it, you should ensure you get one with a long shelf life. This is because you may need it to last a few years because of how infrequent you’ll be using it. 

Fuel additives are recommended to be used every 3,000 or so miles, which will take an average driver around three months to clock up. If you have a large quantity of it, it will need to last for a while before you can use it all up. 

Thankfully, most fuel additives will last at least two years before they expire, so you should have plenty of time to use them before it becomes unusable. 

Pros and cons of fuel additives

There are various benefits to fuel additives, which is why many people who care about the health and quality of their vehicle use them as part of their maintenance plan. With that said, there are also a few things you need to consider which can go against fuel additives. 

Here’s a look at the pros and cons of this compound so that you can decide if it’s right for your car and if adding it is something you want to do in the future. 


  • Fuel additives can make a big difference to the performance of your car, especially if you’ve never used them before. You’ll have more engine power and greater acceleration. 
  • Adding these fuel additives every once in a while will improve the health of your engine, making it live a more prolonged life while keeping it a lot cleaner too. 
  • As fuel additives can clean your fuel system, it means that there are fewer carbon deposits causing blockages, which means that your entire system becomes a lot more efficient. This can give you an increase in mileage. 
  • Fuel additives can make your engine quieter, especially when idling. 
  • Adding fuel additives to your car every once in a while can help you save money, as the prolonged mileage will mean that you don’t need to re-fill as often.  


  • Adding too much fuel additive can damage your engine and fuel system, causing clogs in your filter system, which can impact the performance and efficiency of your vehicle. 
  • Not all fuel additives are EPA-approved, meaning they may not be the most environmentally friendly options. As most fuel additives will be removing carbon from your vehicle, not having an EPA rating may mean that harmful carbon is not being treated responsibly.
  • There are a lot of different fuel additives that focus on different things. This can make finding the right one for you much more challanging

As you can see, there are not many negatives about fuel additives. In fact, if you’re careful, don’t use too much, and ensure to buy environmentally friendly options, you can easily eliminate these negatives. Fuel additives can do so much for your car, and it’s something that everyone should start to consider including in their car maintenance routine.

Fuel Additives FAQs

Fuel additives can be used in any weather condition, making them a perfect option for your car all year round. Not only are they suitable for the winter, but that’s the season where you can see the most benefits. 

This is because fuel additives remove water from your fuel by absorbing it. This can prevent freezing within the fuel system, ensuring that things don’t get damaged and that your engine works as well as it can. 

It’s possible to add too much fuel additive to your vehicle, and doing so can cause harm to your engine and other parts within the fuel system. Too much fuel additive can clog features such as the filter, meaning it’s less efficient and powerful. This can also cause engine failure in serious situations. 

To prevent using too much fuel additive, make sure only to use the amount stated on the bottle. The recommended amount can change from brand to brand, so check how much to use before adding your fuel additive. 

Many people are put off adding a fuel additive because they consider it an unnecessary extra expense. The truth is that fuel additives aren’t that costly, costing under £10 a bottle in most cases, and usually, these bottles can last a few treatments as well. 

You’re not adding fuel additives every time you fill up your car, so it’s not an expense you’re paying for all the time, making it a much more affordable option. Instead, you’ll be using fuel additives every three months or so, so it’s not something that you’ll have to purchase regularly. 

Plus, fuel additives can help you save money in the long run. Because they’re able to improve your mileage to the gallon, you’ll be able to drive further before needing to refill. This can save you money, as you’re not going to the petrol station as often, which is even more important due to the current fuel cost.

Fuel additives can also prevent your fuel system from breaking down, stopping you from paying a lot for a mechanic to fix it. This all means that fuel additive is affordable, and continuous use can help you save money in the future. 

There are many different fuel additives and brands to choose from, making it challenging to figure out which one is the best you should get. Unfortunately, there’s no definitive answer, as the best fuel additive for you will be the one that provides the specific results you’re looking for. 

If you’re looking to clean your fuel system, one type of fuel additive will be better than another. If you want to improve your octane levels for a more efficient drive, then a specific type of fuel additive will work better than another. 

You’ll need to carefully consider what type of fuel additive is best for your situation while also factoring in things like price, size, shelf-life, and more. 

With that all said, if you’re just looking for a fuel additive for regular maintenance, some options provide benefits in many different areas, and these options that offer a range of benefits are the ones that you should go for. 

Fuel additives are something that you use pretty infrequently. Instead of adding them every time you refuel your car, you should do them after every 3,000 miles you drive. For the average driver, it’ll take around three months to achieve this distance, meaning that you should aim to add fuel additives four times a year. 

However, if you want a more accurate idea, you should also look at your manufactures handbook, which will give you their recommendations on how often fuel additives should be added.

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