Glad to bump this message in order to report the same experience for myself. When I started oil pulling I read that some people claimed to have less gray hair, but I stashed that information away and almost forgot about it as I was more interested in how the oil pulling could help my inflammation issues. Well, after a month of oil pulling, I took a good close look at my hair roots to see it if was time to "touch up" the hair color. I was happy to see that there is a lot less gray in the roots. The dark hair is not quite as dark as my natural color was, but there is absolutely a lot more of the darker roots than there is of the gray. No doubt about it. I hope that eventually there is enough of the darker roots to be able to completely stop dying my hair. I already know it's an unhealthy practice, but alas, vanity rules once in a while.
I use hemp seed oil for the massage and oil pulling, but I also ingest a lot of coconut oil throughout the day.