The QS Defy oil has been through several changes (marketing and content) since its first introduction. The first virgin oil analysis posted on Bobistheoilguy didn't indicate the same level of zddp that many perceived. It might have had "boosted levels", but the resultant levels were no where as high as Rotella T 15W-40, at the time. Not sure if it's currently near the 1000ppm level. BUT there are other parts of the additive pack which do the same thing as zddp, without them being zddp. Be that as it may.
I've got an old NOS quart of Arco Graphite motor oil, from the middle 1970s. it starts BLACK due to the graphite in the oil. There used to be a motor oil from Louisiana under the brand name of "Long" which had (maybe?) 30% "Moly" in it. The main selling point was the moly in the oil, but never could find out how strong the base oil was.
As for my "sensitive" seat-of-the-pants . . . when I got the engine swapped in one of my cars, I told the mechanic to put the oil in it he was comfortable with, which turned out to be Valvoline 30. I ran that until about 6K miles, then changed it to Castrol 20W-50, which is what I used on the first engine, from the start. After that oil change, I noticed an immediate drop in crispness of throttle response. Not major, but enough for me to notice. I ran it a few weeks to make sure I wasn't imagining things, then changed it for Castrol 10W-40, and "the edge" came back to very similar levels as with the 30 Valvoline. Later changed to Rotella T 5W-40 synthetic, for the zddp levels and the fact it was synthetic.
Whatever works . . .
CBODY67