I have run alot of diff. engines inverted, from smaller os 70 4 strokes to larger 2 strokes it is all in the tweaking of the needles. I was told a couple of years by a flying friend, that most all engine manufactures require a min. of 16% oil. Most 2 stroke fuels are 18 - 20% oil content & to use the sig 4 Stroke fuel the red with castor which I did and still do. The reduction in oil helps keep the glow plug from fowling out. I also use a type F plug it is alot hotter. these are just a couple of my thoughts, GOOD LUCK AND HAVE FUN, Plane looks great.....