As I recall, when the Ultra Low Sulfur hit the scene and the engines were failing, adding motor oil to the fuel was said to prevent pump failure. I then heard that the zero sulfur BioD was even better at lubing and B10 was supposed to be a fix.
Excerpt from: http://www.biodiesel.org/pdf_files/fuelfactsheets/Lubricity.PDF
A 1998 review paper on fuel lubricity worldwide2 showed that diesel fuel in the US and
Canada is some of the poorest lubricity fuel found in the entire world (see Figure 1
attached). Of the 27 countries surveyed, only Canada, Switzerland, Poland and Taiwan
had poorer lubricity fuel than the US. With a mean fuel lubricity of just under the
recommended specification of an HFRR wear scar diameter of 460 microns, fully 50% of
the US fuel was found to be above that recommended by equipment manufacturers.
These US data are with diesel fuel refined to meet the current EPA restriction of 500 ppm
maximum sulfur specification. The severe hyrdrotreating required to reduce fuel sulfur
to the new EPA 2006 specification of 15 ppm sulfur maximum will cause a further
reduction in fuel lubricity compared to today’s diesel fuel, and is of concern to engine
and fuel injection equipment manufacturers.
Lubricity Benefits Provided by Biodiesel
The addition of biodiesel, even in very small quantities, has been shown to provide
increases in fuel lubricity using a variety of bench scale test methods. A diagram of the
various testing apparatus can be seen in chart provided by Lucas (attached). The two
most popular bench test methods for lubricity are the Ball on Cylinder Lubricity
Evaluator (BOCLE), and the High Frequency Reciprocating Rig (HFRR). The BOCLE is
commonly used to evaluate the lubricity of fuels or fuel blends but does a poor job of
characterizing the lubricity of fuels containing lubricity additives, while the HFRR is
commonly used for both the neat fuels and with fuels containing small amounts of
lubricity enhancing additives. end quote
It stands without question that fuel quality is regulated by the respective Gummints in every country mentioned(and not mentioned). It would seem that the Europeans are more effective at protecting us from the abuses of the oil refiners than our domestic brand of Gummint. I spent three years over there in the late 60's and never once noticed a D truck belching smoke and the Pa Turnpike was awash in them and I thought all that black smoke was "normal". I haven't located the authoritative paper on the subject but I did read a few years ago that the D engines lasted longer in E and ran cleaner thru their life span.