There is a wide range of prices for bottled DEF in the current marketplace. For users, it is critical to assure the proper fluid is being used and not a “similar” fluid with possible chemical contamination that could cause premature catalyst failure on their vehicles. This will be extremely expensive.
Users should be aware that API (the American Petroleum Institute) is the agency certifying the product. Currently there is no law that requires DEF producers to get this certification nor even to require them to meet the ISO standard for DEF. However, to assure that the fluid is properly produced, one can check the producers listed on the API web site at http://www.apidef.org/searchresults.asp which presents those who are certified.
This information needs to be highlighted as part of the user education which is sorely needed regarding SCR Technology and the fluid. If you are using DEF make sure the product has the API certification mark on the label (not something that looks similar to the mark) before you buy or pour it into your DEF tank.