Sig Champion 1/2-1/2 castor/synthetic, nitro 5-15% per your engine, plane, altutude conditions.
I use the 15% nitro as I fly at 5K' altitude but 10% is acceptable, if thats all I can get at the time of purchase.
Also I also boost castor up 2-4% if engines are not behaving like they normally do.
Powermaster is good stuff, if you can get 1/2-1/2 castor/synthetic blend locally.
!0% nitro should be right at your location but if you go to a flying site a more than a couple thousand ft. altitude, bring 15% nitro also.
Jerry