You may think that using your own watered down leave-in hair conditioner is good enough, but if you’ve adopted a natural shampoo hair routine or need a little extra nourishment to bring your dry hair back to life, a deeper moisturizing treatment may be just what your hair needs. An oil-based leave-in conditioner or hair serum can help tame wild flyaways, soften brittle hair in dry temperatures, or protect a healthy head of hair.