The best diesel engine cleaner

Improve power and increase fuel efficiency with a good diesel fuel cleaner.

best diesel engine cleaners

by Ryan Gilmore |
Updated on

In a world where the fuel is becoming less and less popular, why are diesel engine cleaners important as a fuel additive? The unmistakable clatter of a diesel engine is becoming a rarer sound nowadays. But in contrast to what manufacturers and governments are pushing towards nowadays, there are still masses of old diesels on the road.

Until 2035, there will be a place on our roads for diesel cars. If you're travelling long distances on motorways, the fuel efficiency of a diesel engine is almost unbeatable. The outside lanes of the M1 and other busy roads are still awash with Mercedes E350Ds and Audi A4 TDIs. Diesel may not be popular, but they are still important to everyday lives.

One of the drawbacks of diesel, however, is carbon deposits that naturally build up over time. These hard carbon deposits reduce performance and engine efficiency, so it's a good idea to get them removed. Thankfully there are a number of fuel additives available that'll flush these deposits out as you drive along. And in case you're wondering, petrol engine cleaners are on the market as well.

The best diesel engine cleaners at a glance:

Editor's pick: STP 5-in-1 Diesel Cleaner - buy from Amazon.
Best value: Redex Diesel System Cleaner - buy from Amazon.
Best for high mileage: STP High Mileage Injector Cleaner - buy from Amazon.

We've already covered diesel injector cleaners, but there are more additives designed for different purposes. Let us guide you through the best diesel engine cleaners on the market.

The best diesel engine cleaners

Editor's pick

best diesel engine cleanersVia STP

A diesel engine's equivalent of a juice-cleanse, the STP 5-in-1 cleaner will flush out deposits, restoring lost power and boosting overall fuel economy. The 5-in-1 also works as a preventative measure against further deposits building up.


  • Great for removing deposits
  • Improves engine power


  • MPG boost is debatable

Best value diesel engine cleaner

best diesel engine cleanersVia Redex

One of the best value options out there is the Diesel System Cleaner by Redex. It helps remove carbon deposits that build up on your fuel injectors, and if they were badly clogged before, you'll restore a bit of performance and efficiency to your engine.

Redex also produce a petrol system variant of this product too, which also massively helps with engine smoothness and cleanliness.


  • Good value for the quantity
  • Can be used in every tank


  • Isn't as thorough as the other products

Best diesel turbo cleaner

best diesel engine cleanersVia Wynn's

If your turbocharged diesel engine is missing some boost (sorry), then it may be partially blocked from deposit build-ups. Wynn's Diesel Turbo Cleaner is designed to clear these turbochargers and restore lost performance to your engine. Obviously, make sure your car is a turbo diesel before purchasing.


  • Helps restore performance
  • Helps save turbochargers from expensive replacement costs


  • Only works with turbo diesel engines

Best DPF cleaner

best diesel engine cleanersVia Wynn's
Price: $22.50

A diesel particulate filter (DPF) will reduce soot emissions and make a diesel engine cleaner. However, DPFs can get clogged with soot easily, reducing engine power and decreasing fuel efficiency. This particulate cleaner from Wynn's will remove these soot emissions, making your engine run smoother and cleaner.


  • Reduces soot emissions
  • Avoid DPF maintenance costs


  • Doesn't target other areas of the engine

Best for high mileage vehicles

best diesel engine cleanersVia STP

As cars get older, they inevitably start to run less efficiently. This highly concentrated additive from STP is specially formulated for cars with higher miles on the clock to remove stubborn deposits and boost engine power. It will also help protect your engine too.


  • Perfect for cars with over 75,000 miles on the odometer
  • Protects your engine


  • Newer/low-mileage cars will not show any difference

Best EGR cleaner

best diesel engine cleanersVia Wynn's

The EGR (Exhaust Gas Recirculation) system reduces harmful Nitrogen Oxide emissions (N2O) and is important for modern diesel engines. The EGR valve is central to reducing these emissions but can become clogged by particulate build-up. This product from Wynn's is not a fuel additive but an aerosol that cleans the EGR valve, air intake system and inlet valves.


  • Reduces harmful emissions
  • Helps avoid hefty EGR repair bills


  • Will not help injectors or performance

Best for catalytic converters

best diesel engine cleanersVia Cataclean

Perfect for reducing emissions, Cataclean is designed to clean and protect your car's catalytic converter and DPF (diesel particulate filter). This will not only reduce your overall emissions but will help restore performance and increase your overall fuel economy.


  • Reduce emissions
  • Increase fuel economy


  • Negligible performance improvement

What you need to know about diesel engine cleaners:

Why do you need diesel engine cleaner?

Diesel loves to create nasty carbon deposits over time which will make your engine less efficient. The tell-tale signs include black smoke and reluctance during starting. An engine full of deposits will also suffer from less performance and increased fuel usage. That's why these fuel cleaners are so useful, they help dissolve these deposits and restore performance and efficiency.

How to know what engine cleaner to buy

It can be quite hard to diagnose where the deposits are building up in your engine, so for most applications, a generalised cleaner will probably be better. You might even want to try adding an engine oil additive to help things along. If, however, you can pinpoint the issue, a specialised engine cleaner will have insanely good results. Here are the common warning signs:

If you're running a turbo diesel engine and can feel a noticeable loss of power, there's a good chance the turbo could use a cleanout. If you're struggling on start-up and black smoke from the exhaust points to an injector problem, invest in some injector cleaners to prevent these issues. Got an MOT coming up? If you're worried about emissions, then a catalytic converter cleaner could make the difference between a pass and a fail.

Ryan Gilmore is the Deputy Autos and Tools Editor for CAR, specialising in car cleaning and hand tools. With an MA in Automotive Journalism, when he's not testing buckets he can be found looking at old Porsches.

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