Protein sensitive heads usually react pretty negatively to straight coconut oil...you can try testing it on a small section if you'd like to try it though. It will definitely penetrate if you leave it on long enough, it can take from 6 to 14 hours depending on porosity/how much you apply.

I have very coarse strands and low porosity too, I personally can't use straight coconut oil but my hair is fine with it when it's formulated in a product.