The black in the diesel oil is soot from the cylinder walls that gets washed off and into the oil. It is the filters job to get rid of it.
Hotshot would have nothing to do with cleaning the oil. Even their web site says nothing about cleaning the oil.
Couldn't agree more, Bugman.
Heavy truck and diesel mechanic (thankfully retired after 30+ yrs)
'91 F-250 SC 4X4, 5spd. ATS Turbo, 3:55 diff.