The Redex Experiment. How did it work out?

I have been conducting an experiment for the past few months. Every time I’ve filled up the family car, I’ve been adding a bottle or two of Redex fuel additive to see whether it improves the car’s performance. The experiment has now finished and I am in a position to tell you what I think.

What is Redex?

Before I got too carried away, let me provide a quick overview of Redex. As I’ve said, it is a fuel additive and it comes in 90ml bottles.

When you fill up, you add a bottle of Redex to the tank. The solution helps keep the engine clean, in particular the fuel injectors.

Fuel injectors feature several jets, each of which is about the width of a human hair. If they get bunged up, your car won’t run as efficiently as it maybe could.

How did the experiment work?

As you have no doubt gathered, the experiment was very straightforward. I just added a bottle to the tank when I filled up with fuel.

Our family car happens to be a diesel-engine Renault. Needless to say, Redex is also available for petrol-engine cars.

When I first saw the Redex bottles, I was a bit concerned as to how easy it would be to empty them into the tank. In fact, the bottle has been designed very well and the contents pour into the tank with incredible ease. You don’t need to worry about spilling it on your hands or clothes.

What were the results?

This is where things get very interesting. When the experiment got underway, we were getting about 40.2 miles per gallon (mpg).

I can’t deny it, the car gets used for lots of short journeys. They’re the worst kind for fuel efficiency and exactly the kind of journey that hammers the life out of an engine. The gauntlet was well and truly thrown down for Team Redex.

As first, things looked good. You’re supposed to use Redex over a protracted period and the mpg did improve over time to about 40.6mpg. We then had a small upset.

My kids messed about with my car’s dashboard display. For several weeks I was unable to see how many mpg we were doing as I simply couldn’t get the instrument panel to display properly.

This happened to coincide with a cold snap in December, not to mention even more manic rushing around and short-hop car journeys over the Christmas period. I simply couldn’t see what impact the weather and increased number of short journeys was having on our fuel usage.

When I eventually got the instrument panel working again, our car was doing an average of 38.8mpg. The decrease came as a bit of a surprise to say the least.

This concerned me, but I happened to read a comment made by one of Redex’s specialists. He said that it was sometimes necessary to add two bottles of Redex to your car’s fuel tank. This, he said, was a good idea if you’d never used Redex before as there could be a lot of junk to clear from the injectors.

Inspired by his comment, I started double-dosing the car. Sure enough our mpg started to increase. It was a small increase to 39.1 mpg, but at least things were going in the expected direction.

What do I think?

It may have been a little inconsistent and I may have had to double dose the car, but at the end of the day, Redex did indeed seem to improve our car’s fuel efficiency. What the experiment also showed is that you must use it regularly.

I wish I had double-dosed the car from the start. I have a sneaky suspicion this may have produced more consistent results as it would have cleaned those injectors properly form day one.

I am tempted to carry on using Redex for a couple more months. If would be good to see if that upswing continues.

I must also say a few words about the hardcore Redex fans who contacted me during the course of this trial. Yes, believe it or not, Redex has a fanbase and some of these guys keep incredibly detailed information about their vehicle’s performance.

It was fascinating to see a fuel additive brand inspire the kind of loyalty you’d usually associate with a rock band or football team. It proves there must be something about Redex.

What about using fuels that already have additives?

You can, of course, buy superior fuels on the forecourt which have already had additives added to them. The thing is, these additives are not regulated in the UK. What comes out of one pump could be entirely different to what comes out of another.

If you buy standard grade fuels and add Redex to your tank, you are guaranteed consistency as the same ingredients go into every Redex bottle. This brings us on to cost.

Redex is widely available from outlets such as Wilco and Halfords and you can find more information about the product online. You can buy a ‘Boot Pack’ of four bottles for around £8.50. This works out cheaper than buying superior-grade fuels.

In summary, Redex clearly had an impact but I am left wondering if the mpg could have improved even more. If you look at it from a cost-basis, it is a more efficient way of buying fuel than using superior-grade fuels. I would certainly suggest you give it a go, but for the first few weeks I’d suggest double-dose the car when you fill up so those injectors get a thorough cleaning.

Disclosure: This commissioned post was produced in association with Redex. Thoughts and opinions my own.