I agree with what has been said, totally. As of late, I have not been able to get 29% all castor, but I can get Sig 10% nitro and 25% all castor. I add an ounce of Randy's Aero 1 oil per gallon and it works great for me at this altitude, etc..
I use a Red Head 29 in OTS and a Red Head 40, 35, and 19 at various times in Classic.