Ah, right, that I agree with.

Fwiw, OS used to include break-in instructions with their ABC engines that were more suited for ringed engines. The instructions with the AX make more sense for that engine.

Oh, also note that many engines really aren't fully broken in until about a gallon or more of fuel as gone through them. A couple of tanks does most of the breakin, and is good enough for sport flying, but it's far from totally done. The low-speed handling tends to settle last, so with a newish engine, you'll often find that the low speed mixture changes a little during the first gallon or so. That's normal.

Also, some engines break in faster than others. OS's seem to break in faster than most. I'm not totally sure why, I think part of it is the nickle vs chrome liner and part of it might be a better fit/finish on the conrod bushings and better quality bearings. But like I said, I'm not sure. For example, my OS .25FX's all broke in quickly and could settle in to a nice low idle after only a few tanks. While the Magnum .25's and .28's I have took a lot longer to reach the same point.