Of course, Powermaster has long since discontinued "RO-Jett" fuel. This fuel was not "Required" for RO-Jett engines, and it works very well in other engines, and is a useful variant - which substantially less boost/brake on most engines that the Powermaster RC Sport fuel (currently called "Air")
They wouldn't tell me for sure what was in it, aside from 22% total oil, 5% castor/17% synthetic, which is the same as Richard had requested originally. Since it was discontinued, David and I had tried various adjustments to Powermaster 10% "Air" to get it to run the same. David added some castor and some Klotz, which he says replicates the effects, but didn't work the same for me, althougth it was also a useful adjustment to the engine run.
I think I have come a lot closer to the original - add ~4% Klotz KL-198 "Light Techniplate" - a lower-viscosity version of original Techniplate. This is a pure synthetic like Techniplate but substantially lower viscosity. I have run *many* flights with 10% RO-Jett, and swapped back and forth many times. The modified fuel requires the same needle shift, the same difference in launch revs (higher) as switching to "real" RO-Jett (which I still have), and feels the same in air, particularly, feels "stiffer" in the corners, as opposed to falling off, then breaking, and not backing off at some inconvenient moments.
Note that this should also permit you to make your own "15% RO-Jett", for hot weather and higher altitudes.
Brett