Redex Diesel System Cleaner Review – the conclusion

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?

Back in October, we started using Redex Diesel System Cleaner in our 100,000 mile Ford C-Max to see if Redex’s claims of improved economy and smoother running actually held water.

We had no hesitation in trying this out, especially as just about everyone at Cars UK Towers has used Redex at one time or another, and were confident it was safe to use. 

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?

It’s a valid question as you’re shoving additives in to your fuel tank, but the fact is that Redex have been delivering their products for almost 100 years, and are happy to declare that “Redex products will never cause any damage or impairment to your car”, and will do nothing more than provide a “reliable engine-cleaning solution” for users. Which is reassuring.

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?

When we did an interim report on the Redex test last month, we said that two out of the three regular users of the car thought it was running smoother, although one couldn’t notice any difference.

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.

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?

In terms of economy, it’s almost impossible to be absolutely definitive as no two weeks are subject to exactly the same usage, weather or road conditions.

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?

We reckon Redex works out at about 5p extra on every litre of fuel used, but that’s less than the fuel saving we’ve experienced.

But as 5p a litre is about half the extra of ‘Premium’ fuel, it’s pretty cost-effective as a way of getting your fuel system to work more effectively. Strike three.

Will we carry on using Redex?

Yes, we will. But, to be honest, we’ll probably be misers and drop down to using it every other fill-up (which will make it cost just 2.5p per litre of diesel) and see if we notice the C-Max starting to use a bit more fuel, or be less happy when cold.

We can always go back to using it every full tank.

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