That can definitely happen in 8700 miles. Those engines run very hot and also have a flaw in engine design that does not allow the oil to reach specific points on the engine. Later revisions corrected the flaw by increasing the space where it was starving(cannot remember the name of the part or what the fix is called).
You run factory fill dino, drive the car hard, high RPM basically beating the snot out of the oil, or tons and tons of short trips, heavy fuel dilution and it will break. Acidity would rise from many short trips I would think no?