RE: OS 32sx
Here's my OS .32SX-H. I put on an airplane engine head, and am using S&W 15% nitro, 15% syn oil, 5% castor:
APC 10x4 = 14,850
APC 10x5 = 13,350
APC 11x4 = 13,000
It's flying a Lanier Extra 3.25, and I've only got a gallon of fuel through it so far. With a Pitts muffler it has a really nice "bark" to it. Very impressive "little" engine!