i saw the question about castor oil and i did not respond because i have no knowledge or experience with it. i have some and have used it for a couple of little things but not oil pulling. it was actually one of my early experiments in wearing oil.
i see no reason why it cannot be used and your experience is a confirmation of that. i agree that switching oils seems to have an effect on efficacy. even in the mixes i have been using, just switching the mix seems to help and i see no particular oil thats demonstrably better than the other. i can get organic unrefined untoasted sesame so thats what i am using as it is the most highly recommended by the experts. i refuse to pull with hemp or my gourmet olive oil because i eat that. i use a cheaper kind of olive oil to mix with the sesame. thats what i have been using for a while and it is fairly consistent. i am still investigating but it takes time.
sorry i couldnt have been more help on the subject.