Several oils are believed to promote hair health and may indirectly contribute to improved density. Among them, castor oil is often recommended for its potential to nourish the scalp and strengthen hair. The ricinoleic acid in castor oil may stimulate hair follicles, potentially aiding in hair growth. However, individual responses vary, and there's no one-size-fits-all solution. Experimenting with different oils and observing their impact on your hair can help determine what works best for you.