before all the flaming begins about another oil thread and the use of the search function there are many different views on the subject and many threads about it. but if you want a simple answer redline 5W30. now close the thread before the hate begins.
Edit: But do run a good filter, personally I run the royal purple synthetic. It is heavy duty and seems to work very well from the oil tests I have had done along with running a magnetic ring on it.