Thank you for your reply.

I haven't run the engines yet so I can still add more oil to the fuel. The castor oil used in the fuel is Castrol-M oil (castor based oil) and either AeroSynth or MolSyn syntheric oil. Unfortunately I dont have easy access to the fuel brands you mentioned. Its either CoolPower, Magnum or the mix from my hobby pusher which is the one I just listed above. My hobby dealer can mix it any which way I want.

Actually I was of the impression that the need for running castor oil in our engines came from the times before quality synthetic oils where available.

I will try add more castrol M to the mix so I get 25% oil for break-in (15 castor + 10 synthetic) and 10/10 for normal operation. Just a further question: Won't the engines become brown/black and gummed up from the castor?