one thing I would suggest is use a smaller prop which will allow the engine to break in at operating RPM while being well lubed as well as cooled by unburned fuel. I use a 9 x 4 on Fox stunt 35's.

There is an interminable discussion of castor vs synthetic oil on the fuel forum. I fly with Sig Champion 10% nitro 20% oil, 50-50. On my Tower 40, which seems to me to run hot, the oil residue is all clear and colorless, not excessive. With my TD 09, there is oil all over the airplane and it is pink. I think the Tower burns the synthetic. However, the TD 09 runs cooler and the synthetic does not burn but is deposited on the airplane along with the castor.

Jim