the interview experiences, no matter how good or bad they turn out on the day, the tutors would try to make the best decisions. it varies between colleges, tutors and the candidates what sort of interview it would be. in any case, i'd advise simply giving it your all, take a step back and think calmly when told you have answered wrongly, ask for hints if you are really clueless, always willing to try intellectually, always reason out how you come to a conclusion in difficult cases, and be confident and not arrogant; cant say attitude doesnt have a role in selection, i mean they are going to be stuck with you( or maybe not in small cases) if you do get in.
all the best to all applicants. hope you would find your time in oxford enjoyable.