Nice post. I think the misconception that many turbo owners have is that somehow the more expensive Group III Synthetic oils (Mobil 1 or Pennzoil) are better than other Group III Synthetic oils (Super Tech / Kirkland). I see all Group III oils as basically the same.
The only thing that will help them is oils which have the unusual property of cleaning existing stuck piston rings:
Group III Valvoline Restore & Protect (Due to it's secret ingredient that disolves carbon deposits)
or
Group IV HPL with it's high dose of Ester's + AN.
All other Group III's (Mobil 1, Pennzoil, Castrol, Super Tech, Kirkland) are all in the category as: "Not preventing the stuck piston rings"
on engines with piston ring design defects that have pistion ring holes that don't allow proper flow of oil to the piston rings (causing the extreme heat that causes deposits that gets the piston rings stuck). For those engines, 3k OCI with any Group III oil should help.
Perhaps the best solution is four 5k OCI with Valvoline Restore & Protect, perhaps followed by perpetual 5k OCI with Valvoline Restore and Protect.