22/01/2007
In the quest for optimal engine performance and fuel efficiency, car owners are constantly seeking solutions to keep their vehicles running like clockwork. One common area of concern is the fuel system, particularly the fuel injectors, which can become clogged with deposits over time. This build-up can lead to a host of problems, from reduced power to increased fuel consumption. Enter Redex Petrol System Cleaner, a popular fuel additive that promises to tackle these very issues. But does it truly deliver on its promise to keep fuel injectors clear?
Understanding Fuel Injector Deposits
During the combustion process in a petrol engine, various by-products can form and adhere to the internal surfaces of the fuel system, especially the fuel injectors. These deposits, often a sticky residue from incomplete combustion and fuel impurities, can gradually accumulate. When this happens, the precise spray pattern of the fuel injector can be disrupted. Instead of a fine, atomised mist, fuel may be squirted in uneven droplets or even dribbled into the combustion chamber. This inefficiency has several knock-on effects:
- Reduced Fuel Atomisation: Inefficiently sprayed fuel doesn't mix as well with air, leading to incomplete combustion.
- Fuel Wastage: Unburnt fuel is essentially wasted, meaning you get fewer miles per gallon.
- Power Loss: The engine receives a less optimal fuel-air mixture, resulting in a noticeable drop in performance and acceleration.
- Rough Idling: Clogged injectors can cause uneven fuel delivery, leading to a rougher idle.
- Increased Emissions: Incomplete combustion produces more harmful pollutants.
These issues can affect any petrol engine, regardless of age, but are often more pronounced in older vehicles or those that have not had regular maintenance. However, even newer engines can benefit from preventative care.

How Redex Claims to Help
Redex Petrol System Cleaner is specifically formulated to combat these deposit issues. The core mechanism by which it works is by utilising cleaning agents within the additive. When you pour a shot of Redex into your fuel tank, it mixes with the petrol and travels through the entire fuel system, including the fuel lines, fuel pump, and ultimately, the fuel injectors. The cleaning agents are designed to:
- Dissolve Existing Deposits: The chemical formulation aims to break down and dissolve the carbonaceous deposits that have already formed on the injector nozzles.
- Prevent Future Build-up: Once the injectors are clean, Redex aims to create a protective layer or alter the fuel's properties slightly to make it harder for new deposits to adhere.
By keeping the injectors clean and their spray patterns precise, Redex aims to restore the engine's efficiency. This translates to several promised benefits for the driver:
Key Benefits of Using Redex
- Cleans Fuel System: This is the primary function, targeting deposit removal throughout the system.
- Restores Performance: By ensuring optimal fuel delivery, the engine can regain lost power and responsiveness.
- Saves Fuel: Improved combustion efficiency means you get more miles out of every litre of petrol.
- Reduces Emissions: Cleaner combustion leads to lower levels of harmful exhaust gases.
- Protects Against Corrosion from E10 Fuel: A significant added benefit, especially in the UK, is Redex's ability to counteract the potentially corrosive effects of E10 petrol. E10 contains up to 10% ethanol, which can be more aggressive towards certain materials in older fuel systems. Redex's formula includes corrosion inhibitors to mitigate this risk.
- Suitable for All Petrol Engines: This includes traditional internal combustion engines and modern hybrid vehicles that use a petrol engine.
The User Experience: Promises vs. Reality
Redex is marketed as a simple, hassle-free part of a regular car maintenance routine. The application is straightforward: simply pour the recommended amount into your fuel tank, usually when you're filling up. This ease of use is a significant plus for many car owners who may not have the time or inclination for more complex maintenance tasks. The product is widely available and has been a trusted name in the UK for over a century, lending it a degree of credibility.
However, as with many automotive additives, user experiences can be varied. While many drivers report noticeable improvements, such as a smoother engine, better acceleration, and even a slight improvement in fuel economy, others see little to no difference. Several factors can influence the perceived effectiveness of Redex:
- Engine Condition: An engine with heavily fouled injectors is more likely to show a dramatic improvement than one that is already relatively clean due to regular servicing or a different cleaning additive used previously.
- Driving Habits: Frequent short journeys, where the engine doesn't always reach optimal operating temperature, can exacerbate deposit build-up. Drivers who primarily undertake longer journeys may see less benefit.
- Fuel Quality: The quality of the base fuel used can also play a role in deposit formation.
- Subjectivity of Results: Improvements in performance or fuel economy can sometimes be subtle and may be perceived differently by individual drivers.
It's important to manage expectations. Redex is not a miracle cure for severe engine problems. If your car is experiencing significant performance issues, it's always advisable to consult a qualified mechanic to diagnose the underlying cause. Redex is best viewed as a preventative maintenance product or a means to optimise an engine that is already in good working order.
Comparing Redex to Alternatives
The market for fuel additives is vast, with numerous products claiming similar benefits. When considering Redex, it's useful to compare it against other options:
| Feature | Redex Petrol System Cleaner | Generic Fuel Injector Cleaner | High-Performance Fuel Additive |
|---|---|---|---|
| Primary Function | Cleans injectors, prevents deposits, E10 protection | Removes deposits from injectors | May include cleaning, octane boosting, friction reduction |
| Ease of Use | Very Easy (pour in tank) | Easy (pour in tank) | Easy (pour in tank) |
| E10 Protection | Yes | Varies (check product) | Varies (check product) |
| Brand Trust/History | High (over a century) | Variable | Variable |
| Cost | Mid-range | Generally lower | Often higher |
| Potential for Broader Benefits | Focused on fuel system | Focused on fuel system | May offer more diverse benefits |
Redex stands out with its specific focus on fuel system cleaning and its explicit E10 protection, backed by a long-standing brand reputation. While other cleaners might offer similar deposit removal, Redex's formulation is tailored to address the nuances of modern petrol engines, including the challenges posed by ethanol-blended fuels.

Frequently Asked Questions
Q1: How often should I use Redex Petrol System Cleaner?
Redex recommends using a shot of their cleaner regularly as part of your car's maintenance routine. This could mean every few thousand miles or every few months, depending on your driving patterns. Always check the product's instructions for the most accurate guidance.
Q2: Will Redex damage my engine?
No, Redex is formulated to be safe for all petrol engines, including those in hybrid vehicles, when used according to the manufacturer's instructions. It is designed to clean and protect, not to harm.
Q3: Can I use Redex with E5 petrol?
Yes, Redex Petrol System Cleaner can be used safely with both E5 and E10 petrol. Its formula is compatible with E5 and provides protection against the specific issues associated with E10.
Q4: Is there any scientific proof that Redex works?
While Redex has a long history and many satisfied customers, definitive, independent scientific studies proving significant, quantifiable improvements in all vehicles are limited. The effectiveness is often demonstrated through user experience and the chemical action of the cleaning agents.

Q5: What if I have a diesel engine?
Redex offers a separate range of products specifically designed for diesel engines. It is crucial to use the correct formulation for your vehicle's fuel type to ensure effectiveness and avoid potential issues.
Conclusion: A Worthwhile Addition?
So, does Redex fuel system cleaner keep fuel injectors clear? Based on its formulation and the claims made, it is designed to do just that. By dissolving existing deposits and helping to prevent new ones from forming, Redex aims to maintain the optimal spray pattern of your fuel injectors. This, in turn, can lead to a more efficient engine, better performance, and improved fuel economy.
The ease of use and the added protection against E10 fuel make it an attractive option for many drivers looking for a simple way to maintain their petrol vehicle. While results can vary depending on the individual car and its condition, using Redex as a regular part of your car's maintenance routine is a proactive step towards keeping your fuel system clean and your engine running smoothly. For those looking for a trusted, established brand to help keep their fuel injectors pristine, Redex is certainly a contender worth considering.
If you want to read more articles similar to Redex Fuel Additive: Keeping Your Injectors Pristine, you can visit the Maintenance category.
