The Gas/Glow thing is fun, and I have 5 airplanes running Gas/Glow, from 23cc up to 48cc. I find they make more power, start slightly easier, idle slower and smoother, etc. We have found that a quality four stroke glow plug seems to work best.

Is that glow fuel you used 20% oil, or 20% nitro?? If it is 20% nitro, you might find a colder glow plug will work better once you switch to glow operation if you encounter detonation.

As I have mentioned many times here, the standard Gas/Glow mix with 10/10 glow fuel in it ends up at a final oil ratio of approximately 32:1. This is slightly heavy on oil, as most gas engines have a 40 or 50 to 1 recommendation for oil content, but it is not excessive and will be fine.

Doubling the oil content as one does when they use 20% oil glow fuel in the mix, is sure to cause problems with carboning up the engine and is also likely adding to your detonation problem. Further, that extra 10% oil also means you have that much less methanol in the mix, which might cause problems with glow operation, which depends on the catalytic reaction with the methanol and the glow plug to work.

Good luck and have fun,
AV8TOR