

⚡ Unlock your diesel’s hidden power — smoother, cleaner, unstoppable.
HYDRA MAXIMUS is a premium 1-litre diesel fuel injector cleaner and additive that treats up to 500 litres of diesel. Powered by polyetheramine and cetane boosters, it removes carbon deposits, cleans fuel system components including injectors and EGR valves, and enhances fuel combustion for improved engine performance, fuel economy, and reduced emissions. Ideal for highly tuned and aging diesel engines, it also lubricates critical parts to minimize wear and supports smoother cold starts.










| ASIN | B07RN8HZH3 |
| Best Sellers Rank | 12,667 in Automotive ( See Top 100 in Automotive ) 144 in Fuel Systems |
| Brand | HYDRA |
| Customer Reviews | 4.6 4.6 out of 5 stars (934) |
| Date First Available | 9 May 2019 |
| Delivery information | We cannot deliver certain products outside mainland UK ( Details ). We will only be able to confirm if this product can be delivered to your chosen address when you enter your delivery address at checkout. |
| Item Weight | 1.2 kg |
| Manufacturer | Hydra International Ltd |
| Manufacturer part number | HYD63906 |
| Manufacturer reference | HYD63906 |
| Package Dimensions | 27.1 x 19 x 10.7 cm; 1.2 kg |
G**S
Great quality products
This additive definitely does something to the car, there is a fuel saving, but not huge, the big thing for me is the result it has on the engine, with the additive the engine is so much quieter and a lot smoother. Running a 110000 diesel Vauxhall so like to look after the engine. I have been using this company's additives for over a year now and rate these over the big name brands 100%
J**N
Refreshes the fuel system for old diesels, use on sooted up short journeys diesels
Had a check engine light, obd called it as a a fault on an exhaust sensor, so after clearing the fault code, looked around for a good fuel system cleaner. Amazing stuff, put a couple of doses in half a tank of fuel. Before there was a slight unevenness in the running of the engine and although quick once pushed it lacked that initial urgency. Now it is smooth and more responsive. Not really surprising as it is a 16 year old Mercedes 320cdi, fortunately it is pre-dpf, no EGR and mostly motorway driving which all normally leads to a longer engine life, longer product life and so is why it is running well at 195,000 miles. Overtime, despite full scheduled servicing, the injectors start to block, particularly if you run it down to the bottom of the tank and on some of the supermarket fuels and you see a slight reduction in fuel economy, perhaps around 10%. This can kill a car, my last car had injector problems and often the injector proves impossible to remove as it corrodes into the cylinder head over time and so the car had to be scrapped, as uneconomical to repair. These type of products typically unblock injectors and decarbonise the engine but this one also raises the burn efficiency of the fuel resulting in improved performance and economy. Noticeable difference, definitely would recommend. Will report back later after more use and a longer journey test, but the results from the first two 30 mile outings look promising. Might ditch the detachable filler tube as this makes it easier to keep in the car boot, less likely to smell as more containable. Should make the engine last at least another 200,000 miles countryside and motorway driving. This will keep my internal combustion engine going until we have seen off the EV fad. Just need an additive now to clean the roads of ULEZ. Update, after of a couple of months of use it does not seem to improve fuel economy if your engine is already running running well. Probably this works best on engines that run short journeys and so clog up. Next I will try this on the wife’s diesel..
I**N
Effective but difficult to use
I could feel a slight increase in power and mpg, but the product is difficult to use, once you open it, it has a strong chemical smell and it is impossible to close it back sealed. I would rather buy a single use tube.
L**M
Excellent product
Used on a 2007 2.2 Honda Civic i-CTDi. The car always ran pretty smooth due to years of filling up on Shell V-Power diesel. Put this product in with normal diesel and the difference was immediately noticeable. Works out cheaper to buy this and add it to normal diesel than buying premium diesel. Been using this product a few months now after every fill up. Car is more responsive when setting off. Lower revs gives more torque now. BHP has increased when tested. City driving MPG has also gone up by around 8 MPG. The bottle is an awful design and can easily leak. You don't want to keep this product in your home or car though as it is very smelly! The only thing this product DIDN'T do as claimed is clean the EGR Valve. Which was just as filthy as before I started using Maxiumus. Maybe you have to use it for a long long time before it would have any effect on EGR. I will continue to use as it is the best fuel additive I've ever used.
G**4
Car is running much better
I run a 6 year old Renault with the 1.6dci and on the whole it’s a great engine. Since buying the car 6 months ago I’ve changed all the fluids and filters and the car runs perfectly, however I’ve always felt that it was very flat lower in the rev range. Like others I’ve previously used Millers additives in my Diesel cars and can’t say I ever felt much difference so this time I decided to try Hydra’s product - what a difference!! Since adding this at the recommended dosage the car feels noticeably stronger at lower rpm and my mpg has increased by 3mpg on average. I’m now able to drive in higher gears without the engine feeling like it’s labouring all the time and the pickup in any gear feels much better. My engine was always quiet and smooth enough for a diesel, I’d say it’s running a tiny bit quieter and smoother but given my car wasn’t running badly anyway it’s hard to be sure as the difference is so slight - certainly it’s had no negative effect on this at all. Totally agree with the other reviewers, for the price give it a go - it’s not a lot to loose if it doesn’t work for you, but going by my experience a whole lot to gain when it does! I’ll certainly be buying more Maximus going forward. Well done Hydra this is a great product.
G**E
È un ottimo prodotto e posso garantire che già dopo i primi 100 km si vede la differenza,migliore risposta di coppia, motore più fluido anche ai bassi regimi. Continuerò ad usarlo. Sul prezzo purtroppo è vero è un po altino ma sono soldi spesi bene per far vivere più a lungo il motore e le sue parti. Mi sono accorto in più che ho consumato meno additivo Adblue a parità di km e tragitti fatti quindi il prodotto funziona per me. Sui consumi dipende da come la si porta l autovettura cmq un minimo c è di riduzione ma capite bene che le prestazioni saranno superiori a parità di motore.
P**Z
Buen aditivo se usa desde años con un buen resultado en el gasóleo de calefacción, BP. le da una mejora al mismo muy importante ya que no da la típica bocanada de humo al encender el quemador, se saca una vez al año y se puede ver que está la boquilla limpia y sin este aditivo se tenía que desarmar parte del quemador así co limpiar de hollín la caldera, la cual con el aditivo no es necesario y la ultima vez que paso el serv oficial a la revisión no se tocó nada ya que dijo que estaba limpia, no pongo marca de caldera ni el Serv tec y para 7 años que no se atasca el quemador teniendo la precaución de sacarlo y revisar si hay hollín o la boquilla pueda estar sucia. Recomendable si, que evita el engorro de que se apague la caldera por suciedad y estar un día sin calefacción o agua caliente.
A**E
Super produit. Une nette différence est constater si l'on suit bien les recommandation.
A**R
Experimentiere seit Jahren mit verschiedenen Produkten. Maximus hat mich beeindruckt. Meine Mixtur ist 1:1000 Zu Beginn etwas höher dosiert. Wir verwenden es bei einem BMW 320d Mercedes Sprinter 316cdi und einen Ford Transporter Fazit: Der Motor geht schneller auf Drehzahl, der Turbo beginnt früher Leistung aufzubauen. Besserer Kaltstart und ruhiger Motorlauf. Wir haben ca.0,4 Liter weniger Spritverbrauch als vorher. Ist bei uns im Dauereinsatz, saubere Verbrennung,gute Abgaswerte. Bin sehr zufrieden.
L**A
Buon prodotto, facile dosare grazie alla bottiglia con dosatore. Auto più performante, più silenziosa e minori consumi, soprattutto dopo il terzo pieno con questo additivo. Per chi solitamente utilizza diesel hi-tech consiglio di provare a crearlo con questo additivo. Sicuramente si risparmiano soldi e si ha un prodotto migliore
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