If you are not adding castor oil, then you don't have to cook the castor oil with the petro oil(s). Cooking is for poly-ing the castor oil only, and ONLY when a petro oil is present, OR will be in the future when fine tuning the mix for an app. Keep in mind that paraffin, baby oil, ATF comes from petro oil.
A good technique is to mix castor oil and a petro oil at 50/50. Cook that, and store that in a bottle for perpetual mixing use. Now you don't have to cook the lube except just enough to mix all the ingredients for a particular batch of lube. ... felix