Breakin used to have a huge effect on performance back in the days of iron pistons and wide tolerances.

A quality engine today is CNC produced and the alloys are amazing. Experience shows that the OS46AX does not need yesterday's breakin. If you choose to do it, no problem. It'll eventually break in when it finally gets warm enough, and when enough revs have worked in every surface that needs just that. Which happens in a couple of runs anyway.

And if you want to feel more secure no matter what, then add a bit of castor. It won't hurt unless you put way too much into the mix.

Castor isn't magic except for one property. It will stand up to damaging high temperatures. The engine won't see those temps at all unless you screw up the needle adjustment and run the engine too lean. So nowadays it's insurance for them what feels the need of assurance.