Basil:

My "Standard" fuel is 15% Omega, this is the blend with castor oil, the pink fuel. When I say standard I mean it. Same fuel in all engines, from the Cox 0.020 PeeWee on my "Littlest Stick" up to the Saito 4-strokes.

The 6550 K&B isn't the most powerful 60 class engine available, but it will run forever unless you mistreat it. I'm sorry I didn't buy a case lot of them when they were easily available.

Bill.