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Fuel additives are chemicals that we pour into petrol or diesel tanks to help engines run more smoothly. These products can improve how well a car starts, clean the fuel system, and sometimes boost fuel economy. Drivers often use additives for older cars or when fuel quality is uncertain, hoping to keep engines running cleaner for longer.

There are many types of fuel additives, such as cleaners, octane boosters, and stabilisers. Each one works in a different way and is made for a specific job, like breaking up carbon deposits or preventing rust inside the fuel tank. Buying the right kind depends on what our vehicle needs and what issues we want to fix or prevent.

When choosing a fuel additive, it’s important to check that it’s made for our type of fuel—petrol or diesel. We should also look at the ingredients to see if they’re safe for our engine and won’t void our car’s warranty. Some additives contain harsh chemicals that could damage sensors or other engine parts if used too often or incorrectly. A good additive will show clear instructions and list the benefits, so we know what to expect.

With so many options, it helps to focus on our main goal—whether that’s cleaning the engine, boosting power, or protecting fuel during storage. Knowing what matters most makes it easier to pick the right fuel additive for our needs.

Best Fuel Additives

We have researched and selected the top fuel additives available today. Our list highlights products that can help improve engine performance and keep your vehicle running smoothly.

Lucas Fuel Treatment – 1 Gallon (paid link)

For drivers wanting a reliable cleaner that works with petrol and diesel engines, this fuel treatment from Lucas Oil is a practical choice.

Pros

• Helps reduce engine deposits and keeps fuel systems clean
• Supports better fuel economy after regular use
• Suitable for both older and newer engines

Cons

• Bottle size may be bulky for some users
• Might require frequent use for noticeable results
• Not all vehicles have easy fuel tank access

Lucas Fuel Treatment blends detergents and additives aimed at removing deposits from injectors, carburettors, and combustion chambers. By helping fuel burn more completely, we can see an improvement in both emissions and engine efficiency over time.

It is designed for all vehicles, including those with petrol or diesel engines; this makes it a flexible option for various garages. The product cleans and lubricates parts that get dirty with regular driving, which can help maintain long-term engine health.

The 1-gallon bottle treats up to 400 gallons of fuel, so it can last through many fill-ups. While its size may feel inconvenient for those with smaller vehicles, we find this is less of an issue for regular users or those who drive multiple cars. For best results, it’s important to follow the maker’s recommended dosage and use it consistently across multiple tanks.

Archoil AR6500 Diesel Treatment (paid link)

For buyers seeking a diesel additive that addresses many common issues in newer engines, this product is a practical choice.

Pros

• Helps lessen build-up in turbos and diesel particulate filters
• Treats a large amount of fuel per bottle
• Designed to clean, lubricate, and protect fuel systems

Cons

• Cap and spout design can be tricky to handle
• Some may find the bottle bulky
• Higher price compared to a few alternatives

Archoil AR6500 stands out as a diesel additive made to protect and improve the performance of modern diesel engines. It works by cleaning not just the fuel system, but also the post-combustion parts like turbos and DPFs, which is useful for those wanting to maintain reliability. The large bottle size means we can treat up to 400 gallons, making it last for several fill-ups.

We appreciate that AR6500 aims to reduce regeneration events, which is clearly important when using vehicles with DPF systems. It is formulated to boost power and provide a noticeable increase in response, which many diesel owners may value. Lubrication and protection for the fuel system help keep older and newer engines running smoothly.

There are some downsides to mention. The design of the pour spout could make pouring difficult, and the large bottle shape does not suit every user or storage space. Additionally, the price might be above what others cost, so it is something to consider based on budget and frequency of use.

Hot Shot’s Secret Everyday Diesel Treatment (paid link)

For those who want to keep their diesel engine running smoother and more efficiently, this fuel additive gives several useful benefits along with a few points to consider.

Pros

• Boosts fuel efficiency and power
• Helps guard against rust and corrosion
• Improves engine starts in cold weather

Cons

• Bottle design is prone to leaking
• Strong smell can linger after use
• Dose markings are not in metric units

This treatment works to increase the cetane rating, which can result in better performance and improved fuel economy. It can also help to keep the fuel system clean by dispersing moisture and preventing rust, which is helpful for long term engine health.

We appreciate that this product also claims to stabilise stored fuel, which could be useful for those who do not drive their diesel vehicle every day. However, the bottle has been criticised for leaking and the strong odour could be bothersome if spilt.

While the benefits are clear in terms of performance and protection, the packaging could be more robust. Anyone keen on easier, less messy fuelling may want to have gloves handy or pour carefully. Overall, if the need is for a comprehensive diesel additive, we believe this option deserves consideration.

Royal Purple Max-Atomizer Injector Cleaner (paid link)

This fuel additive is a solid pick for those seeking a powerful cleaner that addresses both injector performance and fuel stability.

Pros

• Highly concentrated formula works quickly on clogged injectors
• Helps stabilise ethanol in fuel, reducing related engine problems
• Suitable for a wide range of petrol and diesel engines

Cons

• Higher price per bottle than many everyday options
• Strong formula may not be necessary for every vehicle
• Not supplied in bulk or larger containers

Royal Purple Max-Atomizer stands out for its focused, synthetic approach to cleaning fuel injectors. We see its high concentration of detergents as a strong advantage, especially for newer engines prone to injector issues. Many will appreciate that it tackles not just deposits but also the problems caused by ethanol in today’s fuels.

Ease of use is another benefit here. The product works in both petrol and diesel engines, making it a versatile choice for households with different vehicles. While the price is a bit higher compared to basic cleaners, the performance improvements—like smoother idling and enhanced responsiveness—are points in its favour.

One thing to keep in mind is that this cleaner is highly concentrated, so for vehicles that don’t show obvious injector issues, a gentler or less costly solution may work just as well. However, for those seeking a reliable additive to help restore performance and prevent ethanol breakdown, Royal Purple Max-Atomizer is worth considering.

ATS 505 CRF Fuel System Treatment (paid link)

This is a sensible option for drivers looking to keep engines cleaner and running smoothly for longer.

Pros

• Helps reduce engine wear over time
• Works with most engine and oil types
• Can limit build-up of engine deposits

Cons

• May arrive with minor packaging damage
• Some users see little change in fuel economy
• Higher price compared to basic treatments

ATS 505 CRF Fuel System Treatment stands out for its focus on engine protection and performance. The formula is designed to guard against friction and reduce metal wear, which means our engine parts can last longer with regular use.

A benefit here is its ability to work with different types of oils and engines, whether petrol or diesel. This versatility is useful for families with more than one vehicle or for those who switch between conventional and synthetic oils.

On the downside, shipping issues could lead to dented bottles, and in some cases, users notice only small improvements in fuel efficiency. The cost is also higher than many budget-friendly fuel additives. Still, for those interested in both engine cleanliness and long-term maintenance, ATS 505 CRF Fuel System Treatment (paid link) remains a reliable pick.

Star Tron Enzyme Fuel Treatment (paid link)

This product offers a broad solution for anyone hoping to keep their engine clean, improve fuel stability, and cut down on ethanol-related headaches.

Pros

• Works in a variety of engines and fuel types
• Addresses ethanol issues like lost power and water build-up
• Easy to use with other additives

Cons

• May not fix major mechanical problems
• Needs measuring for best results
• Results can vary with very old fuel

Star Tron Enzyme Fuel Treatment stands out as a versatile option. It’s suitable for nearly any petrol engine, including cars, boats, and smaller tools. The formula helps keep engines running smoothly, even after sitting unused for months.

One big advantage is its focus on solving ethanol-related problems. The treatment helps prevent phase separation and keeps water from causing rust or damage. It also breaks down carbon and gum, which may help fuel burn cleaner and improve efficiency.

While Star Tron is straightforward to add and not picky about mixing with other additives, it may need careful measuring for the best performance. Some stubborn issues, like very old or highly contaminated fuel, may require more attention. Those simply looking for everyday maintenance and fuel stability will likely find it a practical and cost-effective choice.

STA-BIL Fast Fix Small Engine Treatment (paid link)

This is a sensible choice for those wanting an easy way to help small engines run smoother without taking them apart.

Pros

• Helps engines start and run better by cleaning away build-up
• Suitable for many types of small engines, including lawnmowers and generators
• Can remove water from the fuel system

Cons

• Might not fix engines with serious damage or problems
• Not the least expensive fuel additive
• Works best when used exactly as directed

We often face challenges when small engines start acting up or won’t run properly. Using STA-BIL Fast Fix can be a way to tackle problems caused by old fuel or build-up, without having to strip down the entire engine. Many will appreciate that it can work in mowers, chainsaws, and even generators.

What makes this product stand out is its ability to clear out gum and varnish that form in the fuel system over time. It’s designed to clean carburettors and injectors while also helping to prevent water-related issues, a common headache with petrol containing ethanol. Since it treats up to 20 gallons, one small bottle can go a long way.

However, following the instructions is key to getting the best results. We should also remember that if an engine won’t recover after treatment, a mechanic might need to take a look. STA-BIL Fast Fix is a practical option for routine maintenance or as a first step when faced with engine trouble.

B-12 Chemtool Fuel Injector Cleaner (paid link)

This cleaner is a practical choice for those wanting to maintain a cleaner fuel system and support engine performance.

Pros

• Works to break down stubborn fuel deposits quickly
• Safe for use with catalytic converters and oxygen sensors
• Available in different sizes for various needs

Cons

• Strong chemical odour may be unpleasant
• May require multiple treatments for older or very dirty systems
• Not specifically designed for diesel engines

B-12 Chemtool Fuel Injector Cleaner focuses on cleaning the full fuel system, including injectors, tanks, and lines. Its high-energy solvent technology effectively breaks down gum, varnish, and moisture. This helps reduce build-up, which can keep our engines running more smoothly.

We appreciate that it’s engineered to be safe for both catalytic converters and oxygen sensors. Some products may pose risks to these critical components, but this formula avoids that issue. Options for both home and professional use add to its flexibility.

One downside is the strong chemical smell upon use, which some may not like. Multiple applications might be necessary for cars with a lot of build-up. Also, since this cleaner is not designed for diesel engines, it works best for petrol vehicles.

For anyone looking to maintain their petrol engine’s fuel system with a versatile and cost-friendly solution, B-12 Chemtool provides a straightforward choice.

Gumout Multi-System Tune-Up (paid link)

This is a versatile option for those seeking a reliable solution to keep engines clean and running efficiently.

Pros

• Works with petrol, diesel, and ethanol engines
• Cleans multiple engine parts effectively
• Protects against corrosion and fuel deterioration

Cons

• Can be more expensive than basic additives
• Not all benefits may be noticeable immediately
• The container is sometimes reported as dented during delivery

We find Gumout Multi-System Tune-Up stands out because it suits many vehicle types, including high-mileage cars, lawn mowers, and generators. It addresses various forms of engine buildup and helps clean fuel injectors, carburettors, valves, and more. The formula is straightforward; you add it directly to the fuel tank or crankcase.

Having the ability to work with different fuels and engines adds flexibility. It’s useful for those who want one product for several maintenance tasks. In addition, the product helps stabilise fuel and prevent future problems, which can be handy for long-term vehicle care.

Some users may not notice quick or dramatic improvements, especially in newer vehicles. The price is also worth noting, as it sits higher compared to simpler fuel additives. Shipping issues like dents in the container have come up, but most feedback focuses on the positive impact on engine cleanliness and performance.

Techron Fuel System Cleaner by Chevron (paid link)

For drivers seeking a reliable all-in-one fuel system cleaner, this option from Chevron stands out for its balanced mix of performance and versatility.

Pros

• Helps restore fuel efficiency and engine power
• Suitable for petrol engines and works with ethanol blends, including E85
• May improve cold starts and reduce rough idling

Cons

• Requires repeat use for ongoing results
• Not a budget pick for regular maintenance
• Some effects may take time to become noticeable

We find that Techron Fuel System Cleaner (paid link) offers a thorough cleaning for essential fuel system parts. The formula targets deposits in injectors, valves, and combustion chambers, which can boost lost performance and make engines feel more responsive. It’s compatible with a wide range of petrol engines, making it flexible for most car owners.

This product also stands out for helping to stabilise fuel and improve starting, especially in colder weather or for vehicles that sit unused for weeks at a time. The fact that it can be used with both standard and ethanol-rich fuels, including flex-fuel vehicles, adds to its appeal.

While there are many positives, ongoing use is recommended to keep seeing benefits, which can add up in cost over time. Not everyone may notice changes straight away, especially if the engine is already well maintained, but for those experiencing issues like rough idling or sluggish performance, it could be worth considering.

Buying Guide

When we shop for fuel additives, we need to think about our vehicle’s needs. Not all products work for every engine. We should check if an additive is suitable for petrol, diesel, or both.

Key features to consider:

• Purpose: Some additives clean injectors, some remove water, and others improve fuel efficiency.
• Ease of use: It helps if the bottle has clear instructions and is easy to pour.
• Frequency: Some are for one-time use, others are meant for regular treatment.

We also have to check the recommended dosage. Too much or too little can reduce effectiveness. Always follow the instructions on the label.

Feature	What to Look For	Why It Matters
Compatibility	Petrol, diesel, or both?	Prevents engine problems
Function	Cleaning, stabilising, etc	Solves specific issues
Dosage	Clear directions	Ensures safe and proper use
Packaging	Easy to handle and pour	Avoids spills and mess

It’s wise to read the ingredient list. Some additives contain harsh chemicals that might not suit all engines. We should avoid additives with too many unknown substances.

We recommend checking the shelf life of the product. Old or expired additives might not work as expected.

If we want to save time, looking for multi-purpose formulas might help, but always be careful they meet our vehicle’s needs. Reading verified user reviews can also tell us how well a product performs.