What are fuel additives? You might be thinking that fuel injector cleaners fall into this category, and you’d be very correct. However, things like diesel injector cleaners are one arm of the fuel additive industry. You can get a whole array of fuel additives with a number of different uses.
For example, you can get diesel cleaner additives that help clean the diesel particulate filter (DPF) as well as fuel stabilisers. A handy selection of fuel additives will even target several areas of an engine, improving overall health and even increasing performance. If driving economically and increasing your MPG is important then some fuel additives are perfect for getting the most miles per pound out of your vehicle. It’s certainly a lot easier to use a fuel additive than trying to convert your car to run on cooking oil to save money instead.
Another good example is E10 fuel (uses at least 10% ethanol) and the danger it poses to older engines. Additives can be added into your fuel to ensure the increased ethanol doesn’t eat your engine. If your car can run E10, then petrol engine cleaners are also great for ensuring engine longevity. It might even be something to consider when deciding whether to buy a petrol or diesel car.
The best fuel additive at a glance
What to look for in a fuel additive
There are several things to note when shopping for a fuel additive. Firstly, the term fuel additive is a general term for any chemical product that you can add to your car to improve performance or efficiency, reduce emissions, or simple prevent corrosions and deposit build up.
There are a few different types of fuel additives including: Fuel injector cleaners, system lubricants, emission reducers, and detergents. Each fuel additive tends to have a primary task, but you can find some that will manage more than one purpose so it’s always good to look for the best additive for your needs, and for your engine.
We would always recommend paying close attention to the compatibility of the fuel additive, as many additives have been specifically formulated for petrol or diesel engines. In some cases using the incorrect fuel additive for your engine might mean that it doesn’t work, but in other cases it could cause damage to your engine.
Each fuel additive with be specially formulated for different tasks and therefore require less or more frequent use than others. Always read the instructions when using fuel additives because some will advise to use the product every few weeks and months, while others will advise on use after a set number of miles. There are even fuel additives that are recommended to use during every fuel stop.
There are several environmental benefits of using a fuel additive too: like reduced carbon emissions and improved fuel economy. In the long run a fuel additive can help improve the life of the engine which not only means that less components will need to be replaced but it also saves you some money too.
To make things easier and cover whatever fuel additives you’ll most likely need, we’ve ranked our favourites with different tasks in mind.
The best fuel additive
Best diesel fuel cleaner (Editor's pick)
In turn, this helps restore a bit of performance back to your engine. You're advised to use it every 400 miles, and it helps to prolong the life of any diesel engine. It helps keep the injectors clean as well, reducing the risk of them being clogged up.
Pros
- Comprehensive fuel system cleaner
- Helps a diesel engine live healthily
Cons
- Isn't effective on EGR valves or DPF filters
Best value fuel injector cleaner
As a result, we're more than happy to include it in our top picks for fuel additives. To get the best out of it, you ideally need to insert some every time you fill up, and your engine will thank you for it. It helps clean the injectors and clear carbon deposits, leading to reduced emissions in older engines.
Pros
- Great value for money
- Very effective at engine cleaning
Cons
- Not as comprehensive as it could be
Best fuel additive for reducing emissions
All of this can drastically reduce your emissions which can lead to a seamless MOT pass. Many older cars tend to fail due to dirty engine internals, causing toxic exhaust gases, so keeping it all clean is one of the simplest ways of maintaining your car.
Pros
- Helps clean and maintain engine health
- Reduces emissions
Cons
- Usage schedule is very specific
Best DPF filter cleaner
This is where Wynn's particulate filter cleaner comes in. It helps clear away the blocking soot without the need of dismantling, and all you need to do is fill it in with your tank of diesel. Wynn's also says it's ideal for urban driving, so it's nice to know that you'll be cleaning your DPF filter on your way to work.
Pros
- Combats against clogged DPF filters
- Very easy to use
Cons
- Isn't as effective on the injectors and other parts
Best fuel addtive for treating E10
It isn't made for diesel engines. For petrol, it cleans the injectors, prevents gum formation between the ethanol and petrol, and treats the engine oil from harmful combustion.
Pros
- A great tool if you have to put E10 in your non-compliant car
- Great value
Cons
- Not for use in diesels
Best lead substitute
It works in a very similar way to oil additives and petrol injector cleaners. It helps clean up carbon deposits, prevents corrosion of the fuel system (caused by excessive amounts of ethanol) and lubricates the soft valve seats.
Pros
- Very useful for classics that run on leaded fuel
- Very good value for money
Cons
- 300ml isn't as generous as it could be
Best for performance
Amsoil says the Performance Improver is ideal for restoring power and performance, while improving fuel economy by up to 5.7%. For most cars one bottle of P.I. should be enough for one tank of fuel every 4000 miles, and larger fuel tanks can take two bottles.
Pros
- Improves fuel economy
- Restores performance
Cons
- Not recommended for two-cycle engines
Best for direct injection engines
The Max Atomizer also claims to stabilise ethanol, so less harm should come to your engine it comes in contact with bad fuel.
Pros
- Cleans clogged fuel injectors
- Stabilises ethanol
Cons
- Slightly more pricey than others
Bets for fuel system
The fuel system cleaner can be used with several fuel types including E10 and E85, and will ensure that your engine has a better level of performance.
Pros
- Knock and ping protection
- Improves fuel economy and performance
Cons
- 300ml isn't as generous as others
Tips for using fuel additives
- Always shop for fuel additives that are compatible with your vehicle and engine.
- Identify the purpose of the fuel additive, whether it be to improve fuel economy or remove carbon deposits.
- Always read the instructions carefully and use as instructed.
- Avoid overusing fuel additives and avoid mixing fuel additives as these can cause harm to your engine.
- Store the additive as instructed on the label – usually in a cool, dry place away from sunlight.
- If in doubt, consult an expert that can advise you on your particular vehicle.
Frequently asked questions about fuel additives
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How often can I use a fuel additive?
Usually, there are instructions on each package detailing how you use each fuel additive. For STP's Fuel System Cleaner, for example, it's advised you insert a full bottle every 400 miles. But they can be a lot more specific than that, referring to Cataclean's Complete Fuel System Cleaner included above.
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Do fuel additives really make a difference?
Yes, yes, and yes again. With diesel engines especially, carbon deposits build up in vital areas such as the injectors, EGR valves, and throughout the fuel lines. Diesel engine additives are fabulous for reducing those deposits and keeping your engine running smoothly. I personally never fill up a tank of petrol in my Mercedes 230E without a bottle of Redex fuel system cleaner. 140,000 miles in, and she simply doesn't feel like it. I've never had an MOT advisory on emissions either, which I suspect says a lot.
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What brands should I look out for?
STP is the royalty in the fuel additive field. They've been in the industry for over 60 years, and it's fair to say its products are tried and tested. Redex, Carlube, and Cataclean are others to keep an eye out for consideration, too. They're each very trusted brands with a specialism in the additive field. Wynn's also provides great fuel injector cleaners and oil additives, should you need to treat your engine to one of those.
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