The latest innovation from O.S. the GGT15 (.90) is the same as the GT15 but it has a special glow plug for ignition. Using 32:1 petrol to Coolpower oil, the engine performed flawlessly excellent idle and steady maximum RPM. As an example 11,312 RPM on a 13/8 propeller and 8,161 on a 16/6 with 1,650 reliable idle.This is the start of a different engine era in my opinion.
Note the card of the new OS G5 plugs (standard plug thread of 1/4" x 32 tpi) and the common type glow power at the start of the video that's all it needs and, when it is started, just like a glow engine, the power is off. Interesting!