Rusty: Based on NO rotary experience, just other stuff, I would still recommend no- detergent, dyno stuff for initial break in, not M-1.  you don't ever get a second chance to make that first impression.

jofarr, soddy tn 

 

I personally think the whole "never use synthetic oil for break-in" recommendation is mostly folklore.  Corvettes, and probably a number of other engines come straight off the assembly line with full synthetic, and they've got a lot more parts to seat that we do.  Sump oil is irrelevant for apex seals, and half irrelevant for side seals.  Oil rings, yeah, those are new.  There's only one new bearing, in the whole engine though.  I think I'll be OK... or not :-)

 

Cheers,

Rusty (John's just worried because he doesn't know what it's like to get to 1400 feet in 30 seconds, or land in less than a mile)