I might be slapped down by someone,but I will bet you cant go wrong using 10% nitro with 20% oil 1/2 synth 1/2 castor,or Powermaster 22% oil 1/2 and 1/2.

Jim wrote: "I might be slapped down by someone, but I will bet you can't go wrong using 10% nitro with 20% oil 1/2 synth 1/2 castor,or Powermaster 22% oil 1/2 and 1/2."

No slap down - I run that mix in ALL my engine except my sparkers. Actually, I run Brodak fuel which is 23% but close enough.

Dan Banjock and I run it in our Fox .35s and it's PERFECT. I also use it in my 4 stroke engines.
I have a Stunt Rocket powered with a 1950 Atwood Triumph .49 and use the same fuel - no problems.

Bob Z.

yea I run the Sig in everything I have fro Stalkers to Doublestars,but my personal opinion is not to go castor crazy.

Hi Jim,

The "OLD" engines HAD to have castor, and lots of it, or they would go south REAL quick.  A ST 46 is a "tweener".  Ball bearings, but still not ABC construction w/sleeve-piston.  That's why the castor helps a touch in them.  The new ABC/ABN/AAC that have ball bearings need almost no castor really.  Just enough to help if the run goes lean and too much heat builds up.  Too much castor in the ST 46 with its ring can cause it to stick, I'm told.