Well, he is close. Currently the sulphur content of diesel is 50 parts per million (ppm). Under Federal legislation this must be reduced to 10ppm by 1 January 2009. I think you might have a wrong idea of why low-sulphur is bad for engines - it isn't just the seals, but mainly the low lubricity of the fuel, and I don't think the fuel companies are doing much if anything to replace the lubricant in diesel - that is why biodiesel is so important as an additive (if not as a replacement) for diesel engines. The Ebay guy is just being enterprising, if not totally honest.