I'm not an expert but I'm currently experimenting with them. I have all that you list but I also have lavender and rosemary essential oils. Castor oil is very thick/heavy and I have only used it to smooth my hairlines or as a preshampoo treatment and that's when I mix in a few drops of peppermint EO for an overnight treatment under a plastic cap. Because I don't like to apply oils directly on my scalp, when I apply this mixture to my hair and wear a plastic cap, I believe the peppermint EO still does it's job because even if it isn't directly on my scalp, I still get that tingling feeling.
For a leave-in, I would use some of the lighter more penetrating oils like jojoba, coconut or avocado oil. So far, I've only added a few drops of rosemary EO and lavender EO to jojoba (or half jojoba half coconut oil mixture) and I like it. I got the idea of these 3 ingredients (jojoba, rosemary and lavender) from an aromatherapy website although the quantities they recommended I didn't like. (They used more EO than the carrier oil, but they explained that they were more familiar with Caucasion hair and that for them carrier oils were too greasy so had to make up the smallest fraction of the recipe). I don't have an exact recipe. I just let a few drops of the EOs drip into a cap containing one application amount of my carrier oil then stir with my finger (I mix just before I used it and just enough for one use). I then pour this mixture onto my palm and rub my palms together and apply to my hair. When I have time (because I'm in braids), I will use two finges and apply to every braid one by one. When I wear a plastic cap for the night after applying the oil concoction, my hair is unbelievably soft and shiny the next morning with no stickiness or greasy feeling. And I know it looks good to everyone else too because the first time I did it, this white lady at work who's seen me wear my braids wavy at least umpteen times before asked me for the first time in two years how I got my hair so nice and wavy.
It's amazing the attention you draw when you look and know you look good.
I know I said I don't have a recipe. One thing to note is that the EOs are very strong. Too much and your eyes will water or your nose will run..and you might burn your scalp. So you need to use less than you think is enough. If you were thinking of using ten drops, use 5 first. If five, use three. A little goes a long way.
Thanks!
