I have been flying for about 28 years and done a lot of hovering that means a lot of heat in my motors,I will allways us . A good sin oil Lubricant with at least 30% nitro and one oz of caster .some thing like , Morgan fuels I add one oz of caster to my fuel , the sin oils can burn but the caster oil is a lot harder to burn . SO if i lean out a motor it want die because it still has oil.If i bye a motor and you bye the same one, the motors will not act the same ..I fell that most people do break in a motor the right way . or just set the lean to far and dry out the oils, In my years The only problem that I have seen is a problem with the carb. the newer motors are ok,If you fell bad than try a os 50. Look and the way they mount thats mostly what you were asking about. Oh ya . I use a os 46 on a ergo 46 with a tune pipe and can do any 3d I think I can handle. and it turns the head some were around 2475rpms thats way to high ..I stay around 2100 rpms max . with a set of vic-blades.