Start by reading the "rc bugman" Oil Test summary
http://www.rcuniverse.com/forum/m_26..._1/key_/tm.htm
Gives both answers and raises new questions.
Some Tuners of aircraft Zenoahs reccomend 6-7% oil for breakin and 3-4% for running. I don't know why they recommend 6-7% if more oil means more heat.....