Gentlemen.....
LSD and ULSD have nothing to do with the life of the engine per say... . that is the block and other moving parts...
Lubricity is the key to life of the fuel delivery system...
While in college and studying fuel systems, we found that the very tight tolerances of the diesel delivery system can't tolerate dirt, water, gasoline or other chemicals that wash away the oil film of the diesel fuel and whats in it... . once you wash away that oil film, the very tight tolerances can gall and than leak... . or not seal... causing excessive fueling and holes in pistons and other related damage... .
We run a fuel conditioner in all our trucks, CAT and Cummins engines to insure that we have that lubricity that's needed... we do it year around... We've also added extra filters on our trucks... a 10 micron course filter and a 2 micron fine filter to stop the dirt...
We have to have at least 500K on the small trucks and close to 1 M miles on the bigger trucks to reduce the cost of ownership, and the 4 cents a gallon we've added to the cost of the fuel is a very cheep price to pay in relationship to the tow bills, and cost to thaw one out if it gels on the road... . or the cost of a set of injectors and/or pump... .
That's how I see it... .