I knew there had to other ways to help these GDI engines stay cleaner. Thank you Buster for finding this.
It seems my former Valvoline Advanced Synthetic 5w30 did a good job of maximizing suspended combustion contaminants.
I'm expecting to see the same - or better, from Valvoline Modern Engine.
My 2.4 GDI engine has seen factory fill and Castrol Edge prior. But I only witnessed blackish cold start exhaust using the Valvoline. So I'm guessing my oil choices and continuing to use cellulose media filters ( which supposedly are best at capturing soot/carbon), are working well. My used oil at 4k (changed this week) was sooty also.
So the idea to get most of this carbon/soot out of my engine and some thru the exhaust, is working.
I know nothing about complex inner engine mechanics. What I see and observe - I comment on. Since I know absolutely nothing mechanically, I won't comment further inside this thread.
I think Red Line is a good choice for a turbo GDI engine at the premium level. Exceptional shear stability, high POE content and strong detergency. The LSPI concerns should be mitigated by ZDP/Moly and ester content.
There is a video where Roy Howell specifically states that one of their primary goals is to capture as much of the combustion byproducts as possible.
Red Line is overkill for many cars - but I'm wondering about switching over to it when I'm done with my VPBR experiment - it seems to be doing something but it's $90 a gallon. RL(not the API approved stuff) and VPBR seem to be similar on a basestock level with VPBR getting more aggressive esters to act like a solvent.