Given that the additives I’ve been using are not performance boosters as such, I wasn’t expecting to feel any noticeable differences to my car’s accelerative qualities. If that was the point, Redex has products like its Petrol Power Booster. Alternatively, I could just fill my tank with premium unleaded fuel, which has a higher octane level than regular unleaded and provides extra power.

There has been no noticeable difference in performance, and I suspect you’d need a laboratory to really show any improvement. In the variable nature of the real world, and in a well-maintained modern car, I couldn’t detect any difference. Below is a table of my last recording before starting withthe Redex products, followed by one tank of the heavy-duty Redex Advanced 5-in-1 system cleaner and then six tanks using the regular Redex petrol system cleaner. Thankfully, now we’re finished, we no longer have a hung jury, with all three saying the C-Max is now noticeably smoother, especially when it, or the weather, is cold. Since May, I’ve been recording my fuel economy every time I fill up the tank – manually noting down the litres added and mileage covered, rather than relying on the car’s trip computer – and adding a dose of Redex to the tank. The second week of our test actually saw the mpg deteriorate by 1.5 mpg from the pre-test week, but it’s been a steady improvement since then and we look to be getting about 3mpg more than we did before. It’s not huge – about 6-7 per cent – but we’ll take it. Strike two. How much does it cost to use Redex?

Each Redex bottle clearly shows how many shots it contains on the front label, with easy guide ‘shot’ marking on the side. Adding more than one shot of Redex won’t do any harm to your car and can give you a more intensive clean, so don’t worry if your pouring isn’t exact. It’s also a really easy to use product, just putting a single bottle of Redex cleaner in to the tank at each full-up, which soon becomes second nature. What have we found in the last few months of using Redex? The initial baseline figure of 30mpg is pretty indicative of my usual fuel economy result, although usually that’s relying on the car’s trip computer reading rather than direct measurement. We’ve been using Redex Diesel System Cleaner in our 100k mile Ford C-Max for a few months to see if it improves performance and economy. Does it work?

The recent cold snap is what convinced our one dissenting voice, as she found the C-Max far less ‘chuggy’ on first start on cold mornings. So strike one for Redex. Has economy improved? Over about 2,000 miles of mainly commuting in three months, my average fuel consumption using the Redex fuel system cleaners was 31.1mpg. My driving circumstances in that time have been a pretty representative example of my usual activities, so superficially it looks like a 1mpg improvement since using Redex. One shot of Redex fuel cleaner is capable of treating a fifty-litre fuel tank, but those who have never used a fuel additive before – or those who own an older car – may wish to use two shots for an intensive clean, particularly during first application. Firstly, if you have an older or higher-mileage car, you are far more likely to see noticeable improvements in performance and fuel economy compared to a newer, lower-mileage vehicle. Given that fuel deposits and debris build up in your engine over time, it makes sense that you’ll notice a greater improvement in an older engine that has seen a few million more fuel explosions than a newer engine. If I’d been running the same test on an older car I am sure I would have seen some more noticeable results, but unfortunately I don’t have an older car to call upon for such a purpose (and buying an old banger to drive for three months didn’t really appeal!) But the one question we’ve had from a number of readers since we first started using it is: Can using Redex damage my car?

Can using Redex damage my car?

Please note though, Redex has been safe-tested at 4 times the recommended dose, so please don’t exceed this. What is the Mix Ratio for Redex? Also, if your tank is larger or smaller than 50 litres you can still use the recommended dosage with same level of performance being achieved. As I’ve made clear previously, this isn’t a laboratory test in controlled conditions but rather a real-world trial that gives a decent indication of what any driver can expect in everyday life. The purpose of the Redex fuel system cleaners is to remove this build-up of deposits and keep the fuel injection system clean. By doing so, the fuel will burn more cleanly and therefore give you better performance and fuel economy as the engine is working more efficiently.