Product review: Redex ‘Petrol System Cleaner’

Over the past few months I’ve been carrying out a trial of Redex in an attempt to find out whether it lives up to its claims.

Before I start – a quick history lesson about “the UK’s number one fuel additive”…

The brand dates back to 1922 when drivers used to get their shot of Redex at petrol stations to improve engine performance.

The use of Redex became an established part of car maintenance and many drivers began to use it whenever they filled up their cars. “Penny a shot” dispensers were used at filling stations. When you filled your car with fuel, you could ask for a shot of Redex with it to keep your car running for longer.

In 1973 Redex was bought by Holts and added to its family of automotive products. Over the years, Redex has innovated and added to its product range to meet the demands of modern cars. In 2017 a new slogan was launched – “for a better drive”.

Redex trial

I have to admit, I’ve always been a bit sceptical about fuel additives, so I welcomed the chance to try Redex ‘Petrol System Cleaner’ on my car.

I chose to run the test on my trusty 2006 Mazda MX-5 2.0 Sport which has done 70,000 miles and runs well – but could it go any better and are there fuel savings to be made?

During combustion, deposits build up on your car’s fuel injectors and lead to an inefficient use of petrol. Apparently, Redex stops this build up and cleans the injectors to save you petrol.

Apart from cleaning your fuel system, it’s also claimed that Redex reduces emissions, restores performance and improves the life of your engine.

I don’t have a crystal ball so I can’t tell you whether it will improve the life of my MX-5’s engine, but I can tell you that it is running particularly smoothly and it pulls away as well as ever.

Over time, most cars lose power and I’m sure my Mazda is no exception. Short of running it on a rolling road, it’s hard to work out whether some of its lost power has been restored. However, I do remember that Fifth Gear episode from 2013 where Jason Plato got an extra 6hp out of an old VW Corrado VR6 after using Redex ‘Petrol System Cleaner’ – and that was a scientific test.

I got through three tanks of fuel during the test period and I’ve added a bottle of Redex each time. I can report that fuel economy was consistently still around the 30-32mpg mark which isn’t bad, but there’s been no radical shift there.

Of course, no month of motoring is identical meaning it’s virtually impossible to compare fuel economy conclusively, so the jury’s out on that one.

All in all, I think I will continue to use Redex, but perhaps limit it to every couple of months, because if nothing else, it makes sense to keep older cars especially running as cleanly and efficiently as possible.

A one-shot Redex treatment, available for diesels and hybrids too, costs around £3.