Half true, EO or mig840 are the thinnest and hold More than castor, and many times is the same for mig812/MCT or they hold the same even so castor is 100 or more times thicker250 cyp
25% BB with thinner oil is ideal
The thinner your oil the more solvent you actually need
Holding power isn't just solvent concentration but also viscosity related
25% will be enough for even a cold transport
But you can do 20% easily but since your using thin mig 812 I recommend 25%
