Castor is only "pressed" once. There is no 2nd and third pressing. The best castor for engines and for health products is "Cold Pressed" castor. Cold pressed means the beans are pressed slowly and the temperature remains below 122 degrees. The second method is "Expeller pressed" and it is rapidly "pressed by a rotary type expeller press and that causes the temperature to exceed 122 degrees which causes the molecular structure of the Castor to change slightly. The third method is "Chemical extraction" and this uses chemicals to get the oil out of the beans.
First or "cold" pressing produces the purest castor but is the most expensive process. Expeller pressed is the next purest and costs less. Chemical is the fastest and cheapest way but it leaves contaminants in the castor, like benzene, and Hexane. oddly, the more you refine castor, the worse it becomes as a lubricant. That's because the quality that makes castor a great lubricant for two stroke high temperature protection is that the hotter it gets, the longer it's molecules become, making it increase in viscosity, rather than decrease like almost all other oils.