Break-in oil & Ross pistons

[Brian]

It is my understanding that running in oil has no friction modifying additives; it is plain mineral oil, designed to allow the rings to quickly bed in. I always change that oil after the first 50 odd miles, thereafter run the oil of your choice.
My experience with those metric rings is that the top rings cannot be filed with a regular file should you need to open up the gap. You'll need a special ring gapping thingee with an abrasive disc that you rotate against the end[s] of ring