The Ultra-Low Sulfur Diesel (ULSD (S-15)) that we started to receive in mid 2006 has shown some dramatically different cold weather characteristics from the earlier High Sulfur (HSD (S-5000)) and Low Sulfur Fuels (LSD (S-500)).
These new characteristics including higher temperature gelling, wax dropout, icing, and difficulty in treating have in the first year and will continue into the foreseeable future to provide some significant challenges to distributors and end users during cold weather.
Due to these new characteristics users in areas of the US where they have not seen cold weather problems in the past, are now and will continue to see serious issues with gelling, wax dropout, and icing.
This is not the end of the world. But I have heard of reports of this causing problems for school buses and the like. Mostly out in western states.