The sulfur actually has nothing to do with the lubricity, it is simply that the process by which they remove the sulfur also destroys the lubricative ability of the diesel fuel.
So the 2 are physically unrelated while procedurally connected, or something like that.....
MMO is not ashless wither, so I would advise against using it. There are some interesting wear test results over on TDIClub, showing that normal treatment with (IIRC) stanadyne is more than enough to bring the lubricity of ULSD up to above acceptable levels.
The lubricity of a fuel is determined by the four ball wear test. The wider the wear scar the lower the lubricity. Bosch advises that the wear scars should be no larger than 400 microns. ULSD must have scars of between 450 and 550 microns. So, by the standards, ULSD is not sufficient for bosch (and many other) injection pumps. Once treated with stanadyne the numbers were down in the 230-330 micron range.
Strange, a product designed for the job did it
