Breaking new rings in


Hi everyone.
Just put the engine of my Kat back in the basket, and was wondering if anyone had any suggestions on the best type of oil to use to break in the rings: regular petroleum or semi-synthetic oil. My mechanic recommends using semi-synthetic, but wanted to know what anyone else thought on this topic.

thanks for all feedback
I was always told to use regular petrolium oil for break in periods. I guess some of the syn's are soo good at protection, that they dont allow things to "wear in"
regular oil is fine for the break in. Switch to synthetic afterward and continue to use it for the life of the bike
When I was just a lad my old man taught me to break an engine in with non detergent oil. Good luck finding one today though. Almost every motor oil on the planet has some package of friction modifiers or anti shear/anti wear additives or? Best to start off with dinosaur based oil, Change it often in the initial break in period and then switch to Synthetic!