Much appreciate a recent discussion of head/piston clearances as it relates to performance and fuel.
For my Brodak 40, which I and others note could use another 500 RPM, I'm considering running 25 or 30% nitro. We'll see how that works out.
For my LA and SF 46 engines, 5% nitro is fine, though I ran too much oil one season, resulting in so much varnish the engine squeaked. While the crock pot / antifreeze method recovered it, I will run 15% synth / 5% castor 2022.
Peter