Well, yeah, the PCM knows what octane the engine is running on. Basically it cares about when knock occurs, and that's the max timing it allows. Since higher octane allows for more timing, you are able to stretch the engine some more. That's why 93 is highly recommended with these engines, even with a stock tune. 87 the engine is barely keeping alive (in performance-speak).
Glad the conventional oil is still working. Have you done a UOA yet?