what is best breakin oil for new motor?

Go with what type your camshaft manufacturer recommends and a weight based on your engine clearances and oiling system design.

I believe Hughes Engines recommends Joe Gibbs break in oil specifically. Of course others are good as well, but they are probably buds and more importantly Hughes knows that if a person uses Joe Gibbs break in oil, that potential failure point (issue) is out of the question.

http://www.hughesengines.com/Index/...IEdpYmJz&level3=QnJlYWstSW4gT2ls&partid=26202

Also, Hughes has a better solution to the zddp issue:

http://www.hughesengines.com/Index/...&submit=Go&searchmode=partnumber&partid=23942