I believe that used to be true but according to their own website it is only 4.5% now. Most top onroad guys agree that whatever it is, it's not enough. I've seen the entire Mugen team dumping an ounce of castor into every gallon on their bench before. It just seems to be required to get onroad motors to stay together at the long periods of sustained high rpms we get on the longer tracks.

One of the best fuels I have ever used for both performance and longevity was only 8% oil but ALL castor while 10% blends have suffered rod bearing failures. So as far as I'm concerned, give me castor or give me death

As for OD, I have no idea what's up with that stuff. It does burn clean like an all synth fuel but seems to run like an all or high castor fuel. I suspect it's high castor with some sort of detergent in it to burn clean but who knows? It's definitely different from virtually everything else.