I have run about 3 tanks of 15% Omega (with 3 ounces of castor added), and the engine seems to be just fine. One unusual feature of this engine is that the cam gear (heli cut gear) is held in place not by ball bearings, but rather by what appear to be bronze bushings. According to the parts manual, both the .54 and the .91 do have ball bearings on the cam gear. I wonder how it will hold up over time, and why bushings only on the .75? All my Saito 4 strokes have bushings on the cam gear and it does not seem to be a problem. It will be interesting to see how it plays out over time. I wish Bill Robison were still here to address this situation. Another question is how does the cam gear get lubrication? The breather nipple is located in the backplate, and after run oil can't reach the cam gear (I think).
Cajuncharley