Fryboy - Before you cook it some more - may I suggest you make a small sample-run of lube first?
Shake the jar real well to mix the oils before you measure up the quantity required for a small batch of lube (you can keep the oils mixed for a couple of minutes before they start to separate again).
Then, if you have no separations within the lube and all looks good, you can go ahead with the rest of the oils.
I too tried more cooking and also at higher temps to no avail. They always separated. One forum member suggested that the castor probably had been converted into longer chains already, even if it didn't hook up with the mineral. And that the stearic acid/sodium stearate/soap would do it's job in keeping the ingredients together.
Most people (including me) have probably done their lube in one sitting thus never observed this oil separation.
Read the posts above, before my heat tests. This separation has been discussed before!