AdBlue® and Car care > Frequently asked questions about AdBlue® > AdBlue®, CLEARNOX®, or CleanR MAX®: What are the differences?

AdBlue®, CLEARNOX®, or CleanR MAX®: What are the differences?

AdBlue, Clearnox or Cleanr Max

AdBlue®, CLEARNOX®, and CleanR MAX® are urea-based solutions for diesel vehicles fitted with SCR (selective catalytic reduction) catalysts. This technology aims to reduce nitrogen oxide (NOx) emissions from diesel engines in order to meet anti-pollution standards. This article looks at the differences between AdBlue®, CLEARNOX® and CleanR MAX®.

What is AdBlue®?

AdBlue® is an aqueous solution composed of demineralised water (67.5%) and urea (32.5%). This solution is injected into the exhaust pipe when engines fitted with an SCR system are started up. Once in the pipe, the urea in AdBlue® is heated to a high temperature and converted into ammonia. This is then sent to the SCR catalyst, which chemically converts the nitrogen oxides into water vapour and harmless nitrogen.

Origins of AdBlue®

AdBlue® was developed in 2005 to meet the European ISO 22241 (or Euro 6) standard for reducing exhaust emissions from heavy goods vehicles. Combined with SCR technology, AdBlue® has enabled a drastic reduction in nitrogen oxide emissions.

Noting the effectiveness of selective catalytic reduction on trucks, some carmakers decided to adapt it to their diesel vehicles from 2009.

But it was in 2015, with the implementation of new anti-pollution standards for diesel cars, that this technology began to appeal to most manufacturers. It was also realised that AdBlue® could have certain disadvantages, particularly for heavy goods vehicles.

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Disadvantages of AdBlue®

In particular conditions, AdBlue® can tend to crystallise, to the point of clogging the SCR catalyst, with the result that the vehicle comes to a standstill. This disadvantage has been observed in particular on commercial vehicles and HGVs that stop frequently (to deliver goods, for example), which prevents the catalyst temperature from reaching a sufficiently high level, and can cause the liquid to crystallise.

AdBlue® has other disadvantages (sensitivity to temperature variations, specific storage conditions, shelf life limited to 18 months, etc.), but these can be avoided by taking a few precautions.

How can I prevent AdBlue® crystallisation?

There are mainly two solutions to prevent AdBlue® crystallisation:

Here we’ll be looking at the first solution, which has the advantage of being an all-in-one package, including AdBlue and anti-crystalliser.

In the additivated AdBlue® category, the best known are CLEARNOX® and CleanR MAX®. Their use is particularly recommended for diesel vehicles facing one or more of the following situations (as is the case for AdBlue® anti-crystallisers):

  • not much distance travelled on a daily basis: if you work from home or your workplace is close to your home, for example
  • regular stops on the same day: this is particularly the case for delivery vehicles, waste collection vehicles and public transport vehicles
  • reduced frequency of use: if your vehicle is parked most of the time and is only used a few days a month or a year (commercial vehicle, agricultural vehicle, worksite vehicle, motor home…)
  • particularly low outdoor temperatures in winter: this applies to you if you live in the mountains, in particular.

CLEARNOX®: to prevent AdBlue® crystallisation

Like AdBlue®, CLEARNOX® is a urea solution used with SCR technology to treat nitrogen oxides. Unlike AdBlue®, CLEARNOX® incorporates specific additives enabling it to keep crystal formation to a minimum, whatever the vehicle’s conditions of use. It is therefore an AdBlue® substitute with special properties.

Launched by Total under the name Diaxol®, CLEARNOX®, thanks to its specific formula, preserves the vehicle’s SCR system and engine by avoiding the crystallisation effect. It meets the same anti-pollution standards as AdBlue®.

CLEARNOX® is particularly suitable for professional vehicles that do not drive very much, or that stop frequently, or that are regularly exposed to very low temperatures.

CleanR MAX®: a solution comparable to CLEARNOX®.

Developed by Renault Trucks Oils, CleanR MAX® is also an alternative to AdBlue®, comparable to Total’s CLEARNOX®.

CleanR MAX® is a formula based on AdBlue®, with additives added to combat the formation of cyanuric acid crystals. As a replacement for AdBlue®, this solution complies with current anti-pollution standards.

Renault Trucks Oils recommends the use of CleanR MAX® for goods vehicles, coaches and buses, tippers, construction machinery, agricultural vehicles and commercial vehicles.

AdBlue®, CleanR MAX® or CLEARNOX®: which one should I choose for my car?

If you use your diesel vehicle in the ‘normal’ way (commuting, shopping, driving, holidays…) and it’s not exposed to too cold a climate in winter, it’s not necessary for you to use liquids other than AdBlue® (see our comparative of the best AdBlue® prices).

On the other hand, if your vehicle (or fleet of vehicles) is in one of the situations mentioned above (frequent stops, low daily or year-round use, or harsh winter weather conditions), the use of an additivated AdBlue® (such as CLEARNOX® or CleanR MAX®) or an anti-crystallisation additive is strongly recommended. This will prevent the formation of crystals in the SCR catalytic converter (or its clogging) and its consequences, which can go as far as bringing the vehicle to a complete standstill. In that case, you’ll need to consider major repair costs, ranging from £250 to over £1,000 for a light vehicle (car or van), and £5,000 or more for a heavy goods vehicle. Enough to make you think twice…

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This article is produced entirely independently of the brands mentioned. Certain links are likely to generate a commission intended to finance the operation of our site. Prices are given for information only and are subject to change.


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