That's 5% nitro and 17% oil (30% Castor/70%synthetic) . It'll work, but it's not my first choice. 15% nitro may give you a bit lower and more reliable idle and a tad more power.

Castor seems to run towards the heat and when it does, it helps lube friction trouble spots. It also helps protect bearings during storage. The down side is, it can burn or "coke", a tar like goo that can stick rings or valves. My opinion is that I'd like to see a small amount of Castor and the majority of the oil synthetic for ring engines.