Is Ad-Blue anti-crystalisation addictive recommended?

[danlat1415]

I have a Citroen C4 Picasso 2017 (5 door) with an Ad-Blue tank.

I've owned the car for 12 months and only done about 8000 miles since I've owned (currently 56,000 odometer)

Iv never had a Ad-Blue car before, and I've not yet had to top up this one. I've not yet had any countdown warnings on the dashboard.

I'm preparing myself for doing it soon.

The filler cap is in the boot footwell next to the spare wheel. It does has some crystallisation around the large black cover, which I assume is from the previous owner/garage not wiping up any spillage.
I've not yet opened the cap to see inside because I thought that was the actual cover and only after watching videos did I see that there is a blue cap cover underneath the top black cover.

I've read about the recall on the blue cap cover with a white vent on top, so I'll check if mine has that when the weather stops raining and I can clear the boot to get access.

I've seen that some people on other cars use an additive into the Ad-Blue tank to prevent crystallisation build up.

Is this recommended? And if so, which would be recommended for use on Citroen (I don't know if they have any specific recommendations like they do with Oil brands).

Also, is there any specific Ad-Blue to get, or all they all equal?

[PaulC5]

When you top up the adblue tank you will find a funnel will help to avoid spilling it in the boot. For our Cactus which also has the filling point in the boot, I pour it from the 10 litre containers into a 1½ litre bottle (again using a funnel) and then from the bottle into the tank. The Cactus uses about 1 to 1½ litres per 1000 miles and the tank is about 17 litres. I have found GSF is one of the cheaper places to buy adblue. If you have the car dealer serviced, not all of them top up the adblue as part of it so something to ask. I would imagine there are not many adblue factories so chances are most brands are the same.

[GiveMeABreak]

I've seen that some people on other cars use an additive into the Ad-Blue tank to prevent crystallisation build up.

Is this recommended? And if so, which would be recommended for use on Citroen (I don't know if they have any specific recommendations like they do with Oil brands).

Also, is there any specific Ad-Blue to get, or all they all equal?

1) Use an Adblue additive like Wynn's or Forte, which you add when topping up the Urea. Make sure you use the domestic vehicle versions of the additive as they do commercial versions! This helps remove and prevent crystallisation in the system. It can really help reduce the build up at the injection point which can cause Adblue faults when the injection rate reduces due to blockages here.

2) Pay particular attention to your specific owner's manual as these systems can be different on the various SCR systems used on different vehicles. Specifically, on the MINIMUM amount to top up and how to top it up with regard to not turning the ignition on for a certain time. All these things are important.

3) The UREA solution should meet PSA standards and must not be diluted or contaminated with anything that may be in an old container that has contained other fluids. The quality of the Adblue solution is monitored.

I top mine up every 3-4 months (depending on my mileage which is pretty low) so I can at least get the minimum top-up amount in. So work out your tank's capacity from your owner manual and the average mileage this will provide, then work out your average expected annual mileage and do the maths to work out the best time to top it up using the minimum amount required. Meter out the anti-adblue crystallisation additive accordingly.

[RichardW]

I'm unconvinced by the additive - the solution is pretty much saturated, so the Urea crystalises out very easily (i.e. if you spill it) - I can't see how a tiny amount of additive is going to stop it dropping out. I imagine that the inside of the tank above the liquid level will be covered in crystals, but these will wash off when the car is moving and the stuff is slosing about. On the other hand, I can't see the additive will do any harm! All adblue is (should be...) ISO 22241 which is 37.5% Urea in 62.5% distilled water so any will work. Avoid those that are stored on garage forecourts in the sun (as this can degrade the urea) or are suspiciously cheap from unknown sources! There is no monitor of the actual fluid - the 'quality' is only monitored via the efficacy of the NOx reduction; if the adblue is being injected, but there is no (or low) NOx conversion, then it will (may) flag a fluid quality error. I think it more important not to overfill the tank and spill it all over the top which might then make its way into the electronics - I just stick 10 litres in ours (about 8k miles) when it asks for it. Must be due soon... Currently B&Q are doing 10 litres of Carlube for £12 which seems a good price as it's gone up, and mostly around £20 for 10 litres now.

[GiveMeABreak]

It contains a lot of nasty stuff looking at the data sheet and reduces light crystallisation / can prevent build up.

I've been using it without incident for years and hope to keep it that way.

[danlat1415]

Thanks for all your comments.
I picked up some Wynn's Crystal Clean Protect from local motor factors today - £8.87
And I'll get some Carlube (10L of Ad-Blue) from B&Q for £11.99 at the weekend.

[Rob hunter]

Folks, reading RichardW's post about the composition of Adblue begs the question - to prevent crystallization why not dilute adblue with distilled water? What would be the pros (if any) and cons of this?

[RichardW]

If you dilute it you will not get sufficient Nox reduction and it will flag the quality error - they've thought of that!

[GiveMeABreak]

For the cost of a bottle of anti crystallisation from any of the manufacturer's it has to be worth it in my opinion to help prevent the faults and issues associated with crystallisation of the components. I can't see them being allowed to market the stuff if it doesn't work. Low exhaust gas temperatures and adverse temperatures can cause crystallisation. That's one reason why the spray pattern is also very important (the science is here: https://sciendo.com/article/10.2478/amns.2020.2.00004)

There are quite a few companies manufacturing solutions to stop crystallisation occurring so my advice is to make sure you don't over-store Adblue, top up your tank when when you can get at least 5-6 litres in (refer to your specific handbook for any minimum volumes to top up and pay specific attention to the period to wait before switching the ignition on where stated). Usage will vary depending on driving conditions for each person / vehicle, but you should be able to get an idea over time as to how much you use in what period and will be able to work it out in future for topping up purposes. Having a fuller Adblue tank will also help insulate from extreme temperatures.

In my case I tend to use a lot more than the suggested 17k miles to a tank of Adblue! So far, I've put in 30 litres to date and have just yesterday topped the tank up and emptied the last of another 10 litre container and the tank was near full as far as I could tell. My vehicle has done 28k miles, so is using more than average, but I would suggest that's because my vehicle is only used once, maybe twice a week on round trips of 36 or 6 miles, so that may be the reason that it uses more.

The main ingredient is Butoxymethylethoxy which is a solvent based chemical and this is what prevents the crystallisation and can reduce / eliminate existing crystallisation in the system.

Kemetyl is another one - this from their website:

Black Arrow Anti Crystal Additive for AdBlue was developed to solve problem with AdBlue which is very susceptible to temperature fluctuations (crystallization when it is very cold and overheating when it is very hot).

Anti Crystal Additive prevents the formation of AdBlue crystals in the SCR circuit (Selective Catalytic Reduction) and in the AdBlue injectors of diesel engines. Main product ingredient
is: [(Butoxymethylethoxy)methylethoxy]propan-1-ol (No CAS: 55934-93-5) min. 95% (w/w).
• Prevents the formation of crystals in the SCR circuit in cold and heat.
• Prevents the AdBlue injectors from clogging.
• Prevents premature catalyst damage and increases its efficiency.
• Accelerates the conversion of urea into ammonia.
• Extends the lifetime of the entire SCR circuit
• Prevents corrosion of the entire exhaust system

So your choice, but I've been using these products for 4 years without issue so far.

[wheeler]

I suppose the question you need to ask is does the vehicle manufacturer recommend or approve the use of theses additives?
If not i would be very weary of using them on cars that are still under warranty, When the dealers are doing the guided fault finding procedure when checking for certain urea system faults part of that process is to take a sample of the adblue fluid from the tank, visually check it for contaminants & measure the specific gravity of it. Im no chemist but i would imagine the additive can change the chemical make up of the adblue & there could be the possibility of it changing readings or maybe give the fluid a different appearance?
If its not approved by the manufacturer there could be the possibility of invalidating your warranty.

[GiveMeABreak]

I don't think that's likely as the dose is so small to be honest and this stuff is widely used on commercial vehicles.

Even totalenergies have a solution (Clearnox) and they state it's tested in collaboration with engine and vehicle manufacturers.