Rabbi Berkovits has said that you should ask your questions to the biggest person you can find who can give your question the time and the expertise it needs, knowing all of your background necessary for the question. Thus, he said as an example, you shouldn't ask Rav Chaim (zatzal) if you should buy a car.
However, his advice was, if Rav Chaim chooses to answer such a question, you should listen to him. It may not be muchrach but Rav Chaim is Rav Chaim...