More information than you really wanted to know...but should know!
Mercedes Benz Selective Catalytic Reduction (SCR) additive Requirement:
Other key specifications for other AdBlue are:
AdBlue® is a 32,5% solution of high-purity urea, used in Euro 4 and 5 vehicles' additional tanks. That permit to reduce emissions of oxides of nitrogen (NOx) from the exhaust of diesel vehicles, by SCR technology (selective catalytic reduction); about the 85% of thes emissions are converted by catalytic reaction into benign nitrogen gas and water, not dangerous for nature.
In the beginning AdBlue® (that can be also called "AUS32", Aqueous Urea Solution 32.5%) must respect some standards: DIN 70070 (quality standard) and DIN 70071 (analytical standard). DIN means "Deutsches Institut fur Normung".
-ISO 22241-1 Quality requirements, specifies the quality characteristics of AdBlue needed to operate the SCR system on your vehicle. It is a final, published International Standard.
-ISO 22241-2 Test methods, specifies test methods required for determination of the quality characteristics of AdBlue. It is also a published International Standard.
-ISO/DIS 22241-3 Handling, transportation and storing, describes how to deal with AdBlue in practice and in its content is much like the CEFIC Quality Assurance Guidance Document.
-ISO/DIS 22241-4 ISO/DIS 22241-4 Refilling interface, describes elements pertaining to refilling components.
Last two ISO are a 'Draft Industrial Standard', and will be published soon.
To assure a good working of AdBlue® storage and dispensing systems and of vehicles with SCR system, it's very important to use only AdBlue® products that match with ISO standards
At the moment the used standard for AdBlue® is ISO 22241 2008/9.
Per Mercedes maintenance Manual Page: 13 "Emissions System Maintenance":
Only use AdBlue® complying with
ISO 22241. Do not add special additives to
AdBlue® and do not dilute AdBlue® with water.
Otherwise, the BlueTEC exhaust gas aftertreatment
system could be damaged.
For the DIY servicing I have found a wide range of prices for the AdBlue or "Urea" additive. From my local dealer the price for 2 liters is $11.00 USD. They will not sell it in bulk ie 5 gallons at a time but only with a full service and even then are unable to break it down on a per liter basis for just the AdBlue additive.
DISCLAIMER: Improper filling and contamination of the AdBlue system WILL result in failure and EXPENSIVE damage to the emissions systems! Any attempt to repair, refill or tend to the system MUST be done with every reasonable measure to insure not external contaminant enters the AdBlue system! NEVER mix anything with the AdBlue additive! The system detects actual NOx output, therefore additive with ONLY the appropriate ISO 22241 Approval can be used to insure proper dosing of the catalysts. Diluting the additive WILL result in damage to the catalysts and a very expensive repair bill.
With that said, here is a listing of suppliers of the AdBlue additive:
IMPEX SKU # 934647
"Diesel Exhaust Fluid"
OEM part number VW/Audi: GUS-052-910-A3 / GUS052910A3 )
OEM Mercedes Equivalant part Number: 004-989-04-20-12
List Price: $14.85 :: Impex Price: $12.83
Verfied to be a quantity of: 9.46L / 2.5 US GAL
NOTE: This can be purchased at any local VW/AUDI dealer
I will continue to add to this as I find more suppliers.