When you say that did you put the Pennzoil in and immediately drain it to change to the Rotella? If you didn't then you were comparing fresh oil against old oil, which is always different. I struggle with the notion that someone's quantitative aural memory is good for 8000 miles or whatever your OCI happened to be.
Even then I question whether the real difference isn't between cold oil and warm.
No, it would take 1000 to 1500 miles. But if I had been subjected to a blind test, I would have gotten it right 100% of the time. It was that apparent. UOA's were excellent with both by the way, I've never thought it had anything to do with wear.