Here's a tidbit about lubricity from Wikipedia:
Sulfur is not a lubricant in of itself, but it can combine with the nickel content in many metal alloys to form a low melting point eutectic alloy that can increase lubricity. The process used to reduce the sulfur also reduces the fuel's lubricating properties. Lubricity is a measure of the fuel's ability to lubricate and protect the various parts of the engine's fuel injection system from wear. The processing required to reduce sulfur to 15 ppm also removes naturally-occurring lubricity agents in diesel fuel. To manage this change ASTM International (formerly the American Society for Testing and Materials) adopted the lubricity specification defined in ASTM D975 for all diesel fuels and this standard went into effect January 1, 2005.[8]
The refining process that removes the sulfur also reduces the aromatic content and density of the fuel, resulting in a minor decrease in the energy content, by about 1%. This decrease in energy content may result in slightly reduced peak power and fuel economy.
The transition to ULSD is not without substantial costs. The US Government has estimated that pump prices for diesel fuel will increase between $.05 and $.25 per gallon as a result of the transition. And, according to the American Petroleum Institute, the domestic refining industry has invested over $8 Billion to comply with the new regulations.
ULSD will run in any engine designed for the ASTM D-975 diesel fuels.
It is, however, known to cause some seals to shrink (Source: Chevron paper) and may cause fuel pump failures in Volkswagen TDI engines used in pre-2009 models. TDI engines from 2009 and on are designed to use ULSD exclusively; biodiesel blends are reported to prevent that failure (Source: HRCCC.org Biodiesel Best Management Practices).
Additives added make up for any lost lubricity. However, apparently some seal shrinkage unrelated to lubricity can occur, which may be the Cummins pump situation.
