ORIGINAL: elad
...you said, I need a good understanding about "Why it's different") why is it different?
The castor oil has much better high temperature lubricating qualities, and carries heat off to a degree that synthetics can not reach.
The .19 won't fly a plane the size of the eagle, so it'll have to go in some small sport plane.
How about an Eaglet? See picture.
Will the fox need a long break-in time? ... AND no muffler...
If the Fox is new, yes, it will take more break in time than you are probably used to.
You can probably still get a muffler from Fox, I have to admit they're good on that.
You might find a new Magnum 0.25 isn't much more expensive, and a lot more powerful.
Bill.