...brings me on to another kind of pollution suppression, namely Ad Blue as used in countless HGVs and Mercedes diesel cars. Unlike the EGR/DPF gubbins, I'm not sure that Bluetec cars run any better or worse without the urea. I hired a C220 CDi recently and there was no mention in the bumpf that came with it about filling up the Ad Blue tank and nothing on the dash (that I could see) that told me if it needed topping up. So perhaps Bluetec type systems could be the biggest emissions scam of them all. Most of these kinds of cars are acquired through leasing companies and are only kept for three years they won't actually have an emissions test until their second owner takes delivery. Perhaps you only have to top it up once a year just before its MOT.
Selective Catalytic Reduction (that's AdBlue to you and me) is perhaps the only NOx control system which actually 'does what it says on the tin' in real world testing. If you believe the various reports on the technology, it keeps NOx emissions within limits in all driving conditions without significantly impacting either economy or performance. It's the system of choice for most current production diesel trucks & buses.
See the following notes from Mercedes, which suggest the tank is large enough to only need refilling as part of the car's normal servicing plan.
If the system is running low, you get a warning message on the dash; if it runs out, the car can't be started.
Read more about it
here.
What is AdBlue® and why is it used?
Mercedes-Benz Genuine AdBlue is composed of urea and de-ionised water. It is injected into the exhaust gasses of selected diesel engines as a post combustion process. Mercedes-Benz vehicles using AdBlue® technology are identified with the ‘BlueTEC’ symbol. AdBlue’s® purpose is to reduce the percentage of harmful NOx (Nitrogen Oxide) found in the vehicle’s emissions. With BlueTEC technology, Mercedes-Benz has been able to heavily reduce exhaust gas emissions while at the same time maintaining the performance of diesel engines in terms of power and torque output.
Where does AdBlue® need to go in the vehicle?
Mercedes-Benz Genuine AdBlue must only be poured into the vehicle’s separate AdBlue® tank –
AdBlue® must not be put into the diesel fuel tank. Do not mix AdBlue® with any additives and do not dilute AdBlue® with water.
How often does AdBlue® need to be used?
The vehicle will not operate unless there is sufficient AdBlue® in the vehicle’s AdBlue® tank. The size of the AdBlue® tank has been designed so that a customer should not have to refill AdBlue® in between service intervals, however an individual vehicle’s AdBlue® consumption may be higher depending on operating conditions.
On average, 1 litre of AdBlue® should last around 1,000km, however usage can be higher depending on how the vehicle is driven and the conditions that the vehicle is subjected to.
• Every A Service AdBlue® tank is refilled / topped up
• Every B Service AdBlue® tank is drained and refilled
If the amount of AdBlue® in the vehicle reaches the minimal level before an A or B Service, a message will appear on the instrument cluster.
Can I use AdBlue® from a bottle that has previously been opened?
No. You should use all of the Mercedes-Benz Genuine AdBlue product in the bottle at the one time and then put the empty bottle in the recycling bin. Once opened and exposed to air, AdBlue® bottles with leftover AdBlue® fluid cannot be stored as the purity of the fluid will be compromised.
Does AdBlue® have a lifespan?
Yes. Due to the limited durability of AdBlue®, AdBlue® has a 2 year lifespan from date of production. It is essential that AdBlue® is stored between minus 5 degrees and 20 degrees Celsius. AdBlue® can decompose if it is stored at 30 degrees or more for extended periods of time - ammonia can form in such instances.