I think they are reffering to the fact that we are supposed to not use Sulfer in diesel or diesel additives as of Jan. 2007. Interesting thing though, all diesels run better with Sulfer so there is a major issue or theory that the traditional longevity of diesel engines my be in jeopardy because of the new law. Many people are reaching for additives, many are trying to use non sulfer additives that protect as good as sulfer additives, or simply having sulfer in the deisel, but the theory is most additives will not make up for the lack of sulfer that the US gov't took out of the fuel. I think they are trying to make new diesel engines run w/o the added sulfer, but I have no information on how that's working out. MMO will add sulfer to the diesel, thus making that vehicle in non compliance with the law, and also put you in jeopardy of voiding the vehicle warranty, EVENTHOUGH the sulfer makes the engine run better, lol. The same law doesn't effect gas engines yet, so MMO still can be sold and used in gas engines eventhough it raises sulfer content. Is my information on that correct guys, or am I way off?