Grapeseed oil is often considered one of the lightest oils for hair due to its small molecular size, allowing for quick absorption without leaving a heavy residue. It's a good choice for fine or oily hair types.

The most lightweight carrier oil is often considered fractionated coconut oil. It's a processed form of coconut oil that remains liquid at room temperature and is easily absorbed without greasiness.

Argan oil is a great lightweight option for overnight use. Apply a small amount to the ends of hair to help moisturize and reduce frizz while you sleep, then wash as usual in the morning.

Rosemary oil, when properly diluted with a carrier oil like grapeseed or jojoba, may promote hair growth. Rosemary oil is thought to stimulate blood circulation in the scalp, which can encourage healthier hair follicles.