I didn't read much, but I did read something that said some doctor or health practitioner checked the oil after doing oil pulling and found much bacteria and parasites in it. I don't see those as a problem, because we're always swallowing them anyway, since they're always in the mouth and they get mixed in with the food and drinks we devour.
I haven't read that anyone has actually gotten an analysis of the "used oil" to see how much heavy metals and other pollutants it may contain. OP has apparently done for me what I've been looking for for over ten years: it's stamped out the infections in my gums, something Dr. Huggins et al never seemed to know how to handle.
If anyone has definitive info on heavy metals and other toxins in the used oil, then I'll consider not swallowing it. But if I stop swallowing it, I'll probably try some cheap oil. I don't like to have good nutrition go to waste.