How to Increase Cetane in Diesel

If you own a diesel car, you may have seen the term “cetane” before – whether at the fuel station or elsewhere. But what does it mean? And does it hold any sway over the long-term health and performance of your vehicle?

Here, we’re taking a closer look at cetane in relation to diesel cars. We’ll highlight what cetane is, how it impacts fuel efficiency and performance, and how – and why – you may wish to consider increasing the cetane count of the diesel you use in your car.

Use the links to navigate or read on below for the complete guide.

What is Cetane?

Cetane is a chemical compound found in diesel. Its combustible nature, coupled with its high energy density, mean it has become a benchmark against which to grade the quality of diesel fuels – much in the same way that octane is used to grade petrol.

It’s for this reason that you might see diesel labelled as “51” on UK fuel forecourts. This number refers to the cetane count, with 51 being the minimum requirement under the EN 590 fuel standard.

So, why does this number matter? And why is the cetane number important?

Generally, the higher the cetane number the more combustible the diesel. And that matters for several reasons, including:

  • Increased fuel economy – cetane helps diesel to burn more efficiently, increasing fuel economy as a result.
  • Fewer emissions – a more efficient burn means fewer hydrocarbons in exhaust fumes, so a higher cetane number is good news from an emissions standpoint.
  • Improved power output and performance – higher-cetane diesel can lead to performance improvements, with noticeable gains in acceleration and all-around performance.

As mentioned, the standard cetane number in the UK is 51 for diesel. It’s recommended that you use diesel with a cetane number above 45 in most diesel cars, particularly those sold in Europe, so the fact that the UK standard is higher than this is a good thing.

What’s more, some premium diesel fuels available to buy in the UK have an even greater cetane number – up to 55, however, this may not be available at every fuel station.

How to Increase Diesel Cetane Number

If you want to increase the cetane number for the fuel you use in your car as a way to improve efficiency or performance, there are a couple of effective ways to achieve this.

The first is simple: switch to a higher cetane diesel fuel. As mentioned above, some fuel stations do stock diesel with a higher cetane rating, so this is an easy and effective way to benefit from the attributes that a higher cetane diesel can provide.

The other thing you can do is use a cetane booster, a type of fuel additive that effectively adds more cetane to each tank of fuel.

The great thing about cetane boosters is that they’re easy to purchase and can be added to any type of diesel fuel. Some fuel stations don’t supply higher-cetane diesel, so a booster additive provides a convenient and readily accessible alternative. Plus, with the cost of diesel subject to volatile price increases, a cetane additive can prove a more affordable option.

Do Cetane Boosters Work?

It’s a perfectly valid question. After all, you want to make sure that the products you use in your car deliver on what they promise, affording a perceptible increase in performance and efficacy.

Of course, we can’t speak for all cetane additives, but our own product, Redex Diesel Booster, does deliver an increased cetane number when used in a tank of standard diesel fuel.

Redex Diesel Booster


Developed in-house by our expert team of chemists, Redex Diesel Booster is capable of increasing the cetane number of a tank of diesel by up to two. Assuming you used standard “51” rated diesel, that puts the total cetane number well within the ballpark of premium diesel fuels.

A cetane increase of two may not sound like much but understand that these are fine margins. The difference between 51-rated diesel and 53 is palpable, with improved power output, maximum performance, greater efficiency, and an all-around better drive.

For more details about how Redex Diesel Booster works, we would recommend visiting our full product page, where you can get to grips with benefits and features, as well as an instructional video on adding it to your vehicle.

Key Takeaways

We hope this guide has helped you to better understand cetane numbers and the benefits that increasing yours can bring. If you take anything away from this guide, make it these key points:

  • Cetane is a chemical compound found in diesel. Its volume is ranked from 0-100, with 51 being the standard cetane number in the UK.
  • Like octane for petrol, cetane is used as a measure of a diesel’s quality and performance.
  • The benefits of a higher cetane level include increased fuel economy, fewer emissions and improved power output and performance.
  • Cetane boosters provide an easy and affordable way to increase the cetane number of a tank of diesel fuel.

For more helpful advice and motoring features, head to the Redex blog. Or tap here for our full range of fuel additives for diesel cars.