I know its Heresy to say, but I'm not in favor of high power break in with mineral oil.
I'm more comfortable with Philips X/C 20-50 and a more modest break in.
That's just me.
I topped my angle valve last year and used Phillips 20-50 to break it in. I read many articles and concluded that mineral oil is like gynecology, old wives tail. Talked to a lot of knowledgable engine guru's that said run it hard on regular oil. After 200 hours my consumption is about a quart every 18-20 hours.
Philips X/C 20W-50 is mineral oil (says so right on the side of the bottle) and is the primary break in oil recommended by Philips. The difference b/w it and Type M is that the Type M doesn't have the AD added.
http://www.phillips66aviation.com/lub_matrix.aspx