Been awhile since i seen it but there were wear tests on Power Service and other additives. I think TCW-3 was the winner for best additive. I think Power Service actually hindered lubricity but its been awhile since i saw that test.
It came in 3rd place.
However, it is the easiest and cheapest of "bottle" additives.
I think bio-diesel came in 1st place for lubricity.
Many of the "bottle additives" on that test were very hard to obtain and expensive.
My Cummins is an older VE pump engine,
so I always add a little 2-stroke oil (and often some used motor oil) to the fuel.