How would you use Castor Oil?

I bought a bottle of castor oil, very high quality, jamaican black castor grade. I wonder how would you use it in a treatment. It used to leave my hair way too greasy and didn't finish but, I remember it help a bit on the scalp making it feel more refreshed. I would leave it at night put on my scalp but the thing is so greasy that i think it may get in contact with the pillow.

you wouldn't

it's useless