In one sentence, it sounds like you're saying testers will drive over 526.1 miles (because you're talking about "losing power")
In another, you're saying testers won't drive far enough to wear off an oil change.
Well if they won't wear off an oil change, they sure as hell won't wear out "stock" oil (which lasts much longer) will they? 
That would depend on the tester, and the amount of duplicate entries.
If you were worried about losing power by not changing oil, when you believed it lost power after a few hundred miles, you would logically have to be worried of exactly that when you do enforce oil changes. (aka you have it backwards)
A la GT5...
The only thing I've seen that is definitely "changed" from GT5, (regarding oil changes and refresh) is that chassis wear out after 500KM instead of 5,000KM. (guessing that is an oopsy)
In which case yes, it will drop to "stock" power, and then be perfectly fine for a grand total of 5,000KM, aka 3,100MI after the last oil change. (which is wildly longer than 124 miles for "fresh" oil)
3,100
Vs
124
Last edited: Jan 16, 2014