HYDRA MAXIMUS : Maximise Diesel Power

Our Price:  £14.75
List Price:  £16.00
Saving Of:  £1.25 (8%)
(Inc. 20% VAT)(£12.29 Exc. VAT)
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  (30 Reviews)
  • Includes ethanol stabiliser to combat the harmful effects of ethanol fuels E5 and E10.
  • Protects and maintains both modern & classic cars.
  • Prevents corrosion in the fuel system and engine components.
  • Safe with catalytic convertors.
  • 500ml Treats Up To 250L of Fuel
  • 5 Litre bottle comes with free dosing bottle
  • Maximum Performance
  • Maximum Fuel Efficiency
  • Maximum Lubrication

Brand:  HYDRA



  • Includes ethanol stabiliser to combat the harmful effects of ethanol fuels E5 and E10.
  • Protects and maintains both modern & classic cars.
  • Prevents corrosion in the fuel system and engine components.
  • Safe with catalytic convertors.
  • 500ml Treats Up To 250L of Diesel Fuel.
  • 5 Litre bottle comes with free dosing bottle.
  • Maximum fuel efficiency 
  • Maximum Lubrication with Reduced Friction  
  • Turns Regular Diesel into Premium + + + Diesel, which is much better than any available filling station premium diesel fuel.


Our additives are specially formulated to help protect your cherished classic car or motor bike from the harsh corrosive nature of fuels containing ethanol.

Ethanol absorbs moisture from the air. When a classic car or motor bike is stored for long periods without being used, this moisture condenses in the fuel tank, fuel lines, carburettors and engine components causing metal components to rust.

Hydra’s additives include a corrosive inhibitor to combat these issues.


Hydra MAXIMUS, we cannot claim it gives your car a jet engine, but with its instant pick-up, smoothness, and power it will certainly feel like one. The best diesel fuel additive you can buy.

Modern diesel engines use high pressure fuel pumps with a pressure of up to 44,000 psi, the fuel is forced through tiny holes in the injector. This high pressure and tiny jet size create a very finely atomised mist of fuel. Creating a fine fuel mist ensures that each molecule of fuel is surrounded by many molecules of air, which contains 20% oxygen. This ensures an efficient fuel burn.  

When the vehicle is new, this process works very efficiently, and the diesel engine operates at optimum performance as designed by the manufacturer. However, over a period of time (within 2,000 miles) deposits of carbon and unburnt fuel start to build-up in the injectors interfering with the correct spray pattern resulting in fuel wastage and higher emissions due to unburnt fuel leaving the engine.

Also, diesel fuels with cetane numbers lower than minimum engine requirements can cause rough engine operation. They are more difficult to start, especially in cold weather.


Many low cetane fuels also increase engine deposits resulting in more smoke, increased exhaust emissions and greater engine wear. The black smoke consists of carbon compounds that have not burned because of local low temperatures when the fuel is not fully atomised.

Low cetane levels in diesel fuel can also result in engine damage over time. When the cetane number of the fuel is low, engine knock and starting trouble can result from delayed ignition. Diesel knock can also occur during idling, giving poor warm up and white smoking after start-up.

These local low temperatures occur at the cylinder walls, and at the surface of large droplets of fuel. At these areas where it is relatively cold, the mixture is rich (contrary to the overall mixture which is lean). The rich mixture has less air to burn and some of the fuel turns into a carbon deposit.

Using fuels which meet engine operating requirements will improve cold starting, reduce smoke during start-up, improve fuel economy, reduce exhaust emissions, improve engine durability, reduce noise and vibration.

Modern high pressure, direct injection diesel engines need high cetane levels to operate at their optimum efficiency. By decreasing the ignition delay, Hydra MAXIMUS gives more time for the diesel fuel to burn and lowers the pressure inside the chamber.

With a better fuel combustion at lower pressure, massive fuel and emission savings are possible.

Hydra MAXIMUS contains the maximum level of cetane booster to ensure that ordinary diesel is turned into Super +++ grade much better than you can buy at the filling station.


A diesel fuel injector cleaner must contain powerful detergents and the best diesel additives contain polyetheramine as in Hydra MAXIMUS these prevent the formation of and, also removes existing deposits caused by fuel decomposition and unburnt fuel down to molecular levels. These deposits interfere with the performance of your diesel engine.


A good diesel fuel cleaner like Hydra MAXIMUS also contains lubricity improvers, that extend the life of injectors and the fuel pump. These lubricants work in very cold climates and do not raise the sulphur level of treated fuel.

Test results give HFRR Wear Profile of less than 300. Our lubricants also reduce the friction in the cylinder thereby improving the coefficient of friction helping fuel economy. Hydra MAXIMUS protects your valuable fuel systems, prevents engine malfunction and engine failures.


Modern high pressure direct injection engines use precise fuel metering through narrow shaped spray channels. Injector deposits mean reduced fuel flow. 100% clean injectors give optimal fuel spray pattern, this results in a very finely atomised spray pattern.   

This means that each finely dispersed particle of fuel is surrounded by many molecules of air (20% oxygen) ensuring a more complete burn. Giving better fuel economy, reduced emissions, and improved engine durability.


Hydra MAXIMUS’s nano-molecular catalyst ingredient introduces additional oxygen to the fuel, this catalyst lowers the auto-ignition fuel temperature, giving a longer burn time.

You are now burning all the fuel instead of blowing some of it through the exhaust system where it will help clog the Exhaust Particle Filter if fitted. The net result is a quieter and smoother running engine with more mpg and reduced exhaust emissions.


The problem with diesel fuel used in boats, generators, farm vehicle etc., is that very often this fuel remains in the fuel tank for extended periods before being used.

As many of us are aware this fuel starts to degrade after only 4 weeks, leading to long term problems and inefficiencies (in a car it is normally used within a week or two).

Hydra’s stabiliser and biocide active ingredients ensure that your fuel remains sweet and stable for much longer.


Independent Laboratory Tests proof that treated diesel still meets EN590:2009 the current EU standard for diesel fuel, therefore your vehicle warranty is not affected by using Hydra MAXIMUS which is the best fuel injector cleaner in the UK.


  1. The most cost-effective additive for diesel engines, to ensure your engine is running at its peak efficiency and economy.
  2. A UK formulated and produced diesel engine additive.
  3. When you need to use a cat cleaner in diesel engine fuel injector cleaner to ensure your diesel engine is running at peak efficiency.
  4. Which is the best diesel cleaner that you can buy? 
  5. How you can you find the best diesel booster for maximum performance from your engine?
  6. How to find the best diesel engine cleaner available today.
  7. How often is diesel engine injector cleaning carried out?
  8. How often should you use a diesel engine treatment. is it every time you refuel?
  9. Diesel engine injector cleaner which is the best one to use?
  10. Which is the best diesel turbo cleaner, that everybody uses?


Use Hydra MAXIMUS it has been designed to overcome all these problems. Product reviews are outstanding, and we do not think that there is a better product on the market.


Dose Rate: 1:500 Use 2ml Hydra MAXIMUS to 1 litres of fuel.


All our products are manufactured to the highest specifications at our UK plant, which is accredited to ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018.


How To Use: Maximus Diesel Power Booster

  1. Remove filling tube from the bottle.
  2. Open the cap on filling chamber and pierce the seal. 
  3. Tightly fit filling tube on the bottle, remove closure from the top of the tube and gently squeeze the bottle to fill the filling chamber with product.
  4. Pour the product directly into your fuel tank, repeat if necessary.
  5. Close the bottle with original cap and store upright to avoid spillage.

Pour directly into fuel tank before or after refueling.

Use only for DIESEL FUEL.

Dose Rate: 1:500 Use 2ml Hydra MAXIMUS to 1 litres of fuel.

When should you use a diesel engine fuel additive?

To ensure your engine is at its peak performance to get the maximum benefits you should use it every time you refuel.

Who makes the best fuel additive for diesel engines in cars, vans, generators, trucks and boats?

Hydra MAXIMUSbrings your treated fuel to the best premium grade that you can buy. It is used in many tuned diesel vehicles which require a premium fuel to run properly.

How can you do a diesel additive test without any equipment?

Simply use your car's mpg trip computer on a regular basis and if your fuel consumption increases then it is time to use a diesel fuel injector cleaner.

Who makes the best diesel fuel injector cleaner, which has lots of 5 stars reviews, and is available for next day delivery in the UK?

Just look at Hydra’s many 5-star reviews from the different channels we sell on. We always have these products in stock for a next working day delivery service.

Why you need the best fuel system cleaner available?

You need to make sure that you are buying a concentrated all-in-one cleaner, that contains detergents, cetane boosters, and lubricants this will ensure that you get the best possible fuel system clean.

I want to use a diesel emission reducer how often should I use it?

To get the best benefits, it should be added to your diesel fuel every time you refuel.

I have an MOT due shortly, when is the best time to use a diesel emission reducer?

Add it to the fuel tank a couple of weeks before the MOT is due, this will give the additive plenty of time to work and clean out your complete system.

Do diesel additives work, or are they snake oil?

A correctly designed fuel additive manufactured by a reputable company will contain cetane boosters, detergents, and lubricity boosters. You will definitely feel the difference within the first tank of treated fuel.

What's the difference between DPB-100 and Maximus?

Hydra DPB-100 when added to normal diesel makes it into premium diesel. Hydra Maximus when added to normal diesel turns it into a higher grade than premium diesel, a grade that you cannot buy at the filling station. Hydra Maximus has been specially created for highly tuned diesel engines where the customer wants to get the maximum performance from their engine.

Can I use it (maybe just one off) to 1:100 ratio? That is 500ml bottle in my 50L tank?

Normally the maximum ratio would be 1:1250, however, we have known people adding the whole bottle to a tank of fuel without any ill effects as a once-off treatment. 

Average Rating (30 Reviews):  
Write a Review and share your opinions!

Thank You! EGR Engine Light Has Gone!
17 June 2022  | 

I have used Maximus as suggested to clear the carbon. The light has gone off! I normally don't leave feedback but my first 5* will be for you! I will promote this product on my social media as best fuel additive! Cheers and I will order again!

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2 of 2 people found this review helpful.

Its not snake oil
02 May 2022  | 

I have been using the Maximus product in my 5 series 2 liter diesel automatic tourer for several months, as my work has increased my mileage and motorway driving I noticed my economy was starting to go down despite using eco mode and driving at a steady speed, having previously owning a car whose DPF got blocked up and being quoted a price for a replacement for an original part (there was no universal part available) which was more than the value of the car I decided to try this treatment after researching on YouTube and seeing favorable reviews. The car does run quieter and feels like it has more torque, economy has improved from 49mpg pre treatment to up to 58mpg naturally the way the car is driven makes a hell of a difference. I have previously tried other manufacturers products and do think there is a lot of crap out there which do little apart from drain your wallet. I bought the 5 liter Maximus product and my only criticism is the measuring bottle which leaks like a sieve and fails to give an accurate dose as when pouring from the measuring chamber the fluid from the main bottle leaks through also which is irritating and I think Hydra should do better with its product, the measuring bottle has to be kept upright inside a zip lock bag otherwise it leaks all over the boot I have found, the cap seals are not to be trusted along with the measuring bottle as a whole. Apart from this I think this is the best product I have tried in terms of fuel additives it also ticks a few boxes which other products will have you buying additional remedies for which to me is a scam playing on those of us not mechanically minded fears.

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4 of 4 people found this review helpful.

16 January 2022  | 

Tried Maximus on 2016 Kadjar Diesel. Very impressive. I definitely felt a positive difference to driving. Quieter, Smoother and can feel the pull. Mileage improved from 53mpg to 64mpg. Given I changed my driving style by limiting to below 70mph, I wouldn't say it was purely because of maximus but certainly it was also a key factor.

Make sure you don't get it in your hands, the smell is horrible. Bottle design must be changed to enable ease of use, so that frequency of use will be higher. Worth giving it a go and see the difference yourself.

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5 of 5 people found this review helpful.

Noticed two things ...
01 January 2022  | 

Prior to finding Hydra Maximus, I usually added a generic fuel treatment or I purchased the "expensive" diesel.
This is my second (500ml) bottle of Hydra Maximus, I was told about this product by a friend but as usual I was sceptical, I had used the last of my old additive and decided to give Hydra Maximus a go, primarily because it was cheaper than the one I was using.
One, I had a small problem with my car (MG ZT 135bhp, BMW M47R engine 149,000 miles) in that I had an injector knock when accelerating, I tried the good fuels and other injector cleaners coupled with an Italian tune up to get rid of this knock without having to have the injectors done but nothing worked.I was resigned to the fact that the injectors were going to have to be changed.
Then I gave my car a double shot of Hydra Maximus to start with and followed it with thrashing on the motorway, a week later and there was no injector knock, it had gone. I use Hydra Maximus in every fill up now, sometimes using a little more than the 2ml to 1l dose, still no injector knock after 5,000 miles.
Secondly I notice that the car accelerates as cleanly as it did when I was paying Shell a fortune for the "good diesel", now I buy my fuel at Sainsbury's and add my own power.
My car also passed the MOT emissions with zero problems too.

I ordered this bottle just before Christmas and was amazed that it arrived next day, post free too I would add. Well packaged and sealed.
If like me you're also a bit sceptical about this product I would just get it to try, really you have little to lose but you might just gain something.

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4 of 4 people found this review helpful.

Great product
24 October 2021  | 

I've been using Hydra Maximus in my diesel Hyundai Tucson for a couple of years now. Halfway through the first tank of treated fuel I noticed that the engine ran sweeter and pulled better. After a few weeks I saw an improvement of about 5% in fuel consumption. This product is far better than the ones commonly found in car accessory shops and supermarkets. Highly recommended.

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1 of 1 people found this review helpful.

Hi There
16 April 2021  | 

I am writing to let you know that I have recently purchased the HYDRA Maximus Power Booster to try in my Mini Cooper 2.0 SD which I virtually always fuel with Shell V power diesel. The car is not used daily but when it is I usually drive 25-30 miles across country on A and B roads to get to my destination. I bought the 500ml size as I was unsure as to it's effectiveness but I have to say that I noticed an almost immediate change in the driving experience and I'm already on my second tank using Maximus! I can honestly say that there has been a very real improvement in the performance of the vehicle. It picks up quicker and overall provides a far punchier experience than standard. The car feels far more eager between bends and the mid range "thump" is impressive. There is a significant difference in everyday driving as the car feels quieter, smoother and doesn't need to be worked so hard. I'm not particularly interested in economy figures and cannot confirm any improvements in that area but I am certainly happy with the improvements in driving dynamics. I will be buying this product from you again! I'm not usually given to writing to companies endorsing their products but in this case I am happy to say that it works and works very well...Thanks!

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7 of 7 people found this review helpful.

Good Afternoon,
09 December 2020  | 

I received my order within 2 days of ordering, it was well packaged, items i ordered were in the package, i have used one of the fuel additives and it appears my car is running smoother now, very pleased with your Company, and the products you sell on Hydra Aqua,
Customer Service is Excellent.
Thank You, Hydra International.

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1 of 1 people found this review helpful.

18 September 2020  | 

My feedback is always the same. As per many positive reviews of your product, you used to supply these bottles with a reinforced ziploc bag which was perfect for storing them (once opened) in my car. I haven't been able to find a similar bag anywhere else and wish you would return to including one with each bottle purchased.


P. Hegan


This review has not been appraised.

New Review
18 September 2020  | 

Great transaction, very impressed with every aspect,
Thank you


This review has not been appraised.

Saved me 3000
06 September 2020  | 

I had a problem with white smoke puffing out my exhaust on start up. Subaru said it was diesel injectors and quoted 3000 because its an engine out job. I bought the diesel injector cleaner and after 1 month of use the smoke has all but gone. I was averaging 500 miles to a tank and since using this I'm now getting around 630 miles to a tank. I'm not saying everyone will be as lucky as me but for the cost of this product it's been amazing. Pretty much saved my car from the scrap heap.

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1 of 1 people found this review helpful.

Read all 30 customer reviews...

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