My new OS 91 Surpass had a different break-in procedure. It called for the engine to be at full throttle and slightly rich (normal run). Then every 10 or 15 sec to adjust the from rich to normal run while at full throttle. Do this for 2 tanks (in the plane). Then for the first 10 flights start at rich and slightly lean to a normal run after 10 flights. I followed the 2 tank bit but couldn't see dogging it through 10 flights to get to normal. I went to normal after the first or second flight. Are both Saito and OS sleeves nickel lined? What is the basic difference in these 2 engines?