Royal Purple Fuel System Cleaner Review

There are literally dozens of different fuel system cleaners available. Each manufacturer claims they make the most effective fuel system cleaner, so we are taking the time to research and investigate the additives currently available.

In this review, we’ll consider Royal Purple fuel system cleaner to see how effective it is and whether it’s worth the money.

What is Royal Purple Fuel System Cleaner?

Royal Purple’s Fuel System cleaner is officially called Royal Purple Max-Clean Fuel System Cleaner and Stabilizer, part number #11722. This synthetic, purple coloured liquid additive is poured into a near empty gas tank, which is then refilled and run as normal.

During this process, the detergents contained within the fuel system cleaner work on the entire fuel system, from the gas tank, fuel lines and rail to the valves, injectors, and piston heads, even right through to the combustion chamber.

It is safe for use with most engines, including gasoline, diesel, bio-fuel, 4 stroke or 2 strokes and it doesn’t affect catalytic converters or diesel particulate filters in any way.

Royal Purple state that using their cleaner will:

  • Increase fuel economy, on average, by 3.2 percent
  • Restore lost horsepower, up to 2.6 percent
  • Lower hydrocarbon, nitrogen oxide (NOx) and carbon monoxide (CO) emissions (in testing by 12, 13 and 18 percent respectively)
  • Eliminate rough idling, throttle hesitation, and stalling tendencies
  • Maintain longer spark plug life by reducing foulding
  • Prevent build-up of carbon deposits that can cause engine knocking and pinging
  • Stabilize fuel for storage
  • Includes corrosion and oxidation inhibitor, vital for high ethanol concentration fuels
  • EPA and CARB compliant

What is Royal Purple made of?

Royal Purple Max-Clean is a proprietary mixture of chemical agents that work as a fuel conditioner. Royal Purple contains around 85% petroleum distillates that have been hydrotreated. The next largest chemical by quantity is Polyolefin alkyl and phenol alkylamine, at around 15%.

It’s surprising that instead of Polyetheramine (PEA), a highly effective carbon dissolving agent, Royal Purple is instead using the above polymers. The rest of the product is made up of solvents, that act as carriers and evaporate during the combustion process, whilst aiding that process too.

How do I use Royal Purple?

Royal Purple is relatively easy to use when compared with some products that require an involved tank emptying procedure and then need to be run at certain road speeds for a specific length of time. Royal Purple does require the fuel tank to be near empty and refilled after treatment, which is one step extra than rivals such as SeaFoam.

One 20oz can is enough to treat 20 gallons, or 75 litres of fuel, which is quite a sizeable fuel tank. Smaller vehicles may get multiple treatments from one bottle.

It is recommended that Royal Purple is used every 10,000 miles as a preventative measure against further despotis forming within the engine.

Does it work?

YouTube user & car enthusiast ChrisFix has tested a range of the most popular fuel system cleaners. He found that Royal Purple actually worked the best out of all the products he tried.

He was not sponsored by any of fuel companies and tested each product on different vehicles using a borescope camera to examine the actual cleaning effectiveness of internal components.

Other reviewers agree, that Royal Purple is an effective fuel system cleaner.

One experienced car owner, whose full-time job is working as a parts manager for a factory rallycross team was impressed. He’d bought an older Jeep Wrangler that had covered around 60,000 miles. The Jeep was suffering from some hesitation under throttle and hadn’t been driven much.

After pouring in an entire bottle of Max-Clean, after just half a tank, the drive was transformed completely. He also tried it in a 1999 Toyota Corolla, again with sluggish throttle response. Again, a can of Max-Clean was used and the sluggish throttle was eliminated.

Another reviewer was skeptical about this kind of product, feeling they what is called ‘snake oil’. However, after purchasing a bottle of RP Max-Clean online and trying it, he found it saved his truck.

Before, the diesel truck was barely running. Within 2 days of running the fuel system treatment through, the truck was running perfectly. The owner had been prepared to replace all the injectors, a costly and timely job, by using a simple fuel system additive, he saved a whole load of money.

As a final example, a 2000 model year Chevy Blazer driver. The fuel gauge had stopped working and the driver thought that the fuel pump might need replacing, adding up to a several hundred dollar bills. The owner tried some Max-Clean in an attempt to clean up the injectors and give it a try, not even thinking about pump and gauge.

After half a tank, the fuel gauge started working again and has done since. A friend of the driver was experiencing the same problems, this time on a Suzuki Jimny. Again, Max-Clean was used and the result was the same, the gauge started operating correctly again.


It’s not the cheapest product by a long shot, but it certainly works and works rather well. Users report promising findings after a treatment of Max-Clean. The packaging of MAx-Clean sets it apart from its rivals, the aluminum tin is study and quality feeling and a pouring spout is included, which is unique out of the fuel system cleaner line-up.

It’s also a neat feature that you can use the product as a storage additive for fuels, which is useful for those that leave in harsh environments or those with seasonal use boats and bikes.

In tests, we’ve seen some solid results and most buyers are happy with the product.

If you are looking for a reliable fuel system cleaner that does as it promises, and are not too fussed about the cost, then this looks like the best option for you and your vehicle.

Royal Purple Max-Clean Fuel System Cleaner is available on Amazon and from most speed part suppliers, such as Jegs.

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