we are in the process of planning our first lengthly stay in south western Arizona/California and northern Mexico (El Golfo De Santa Clara), there are also a couple of trailers that are going to spend three to four months in Mazatlan. Our concern is we have a 2007 Dodge Laramie one ton diesel that uses Ultra Low Sulfur Diesel only, and although there appears to be a lot of new trucks going in and out of Mexico, we understand, ULSD is only available several hundred miles south of the US border and that the ULSD fuel that they do have is imported from the US. ULSD is 15 ppm and the low sulfur diesel they sell in Mexico is 500 ppm, we have been told using the latter plugs up some of the emission filters in 2007 and newer trucks and the manufacturer/dealer threatens to void your warranty. We welcome any comments and/or anyone that has visited Mexico lately. Thanks.