Interesting that you mention the sulphur content issue. Here in Australia where we have various E53 and E70 diesels since 2003, many of the updates with the diesel engines (and there's been lots of them) have coincided with a reduction in diesel fuel sulphur content according to the Australian government mandates. Over the last decade the mandated maximum sulphur content has dropped from literally anything to 5ppm in a series of steps. From memory it first went to 500ppm, the 50ppm (we call that LSD) to 5ppm (our ULSD).