Hair ropan oil & Tea tree essential oil how to use Apply oil to your palm, then dip fingertips in it. Massage the scalp & leave it for 1-2 hours or overnight. Wash hair with a sulfate-free mild shampoo. How To Use Tea Tree Oil Dilute with a carrier oil like almond or coconut oil and apply to the affected area. Add a few drops to your shampoo or conditioner to soothe the scalp. Follow your physician’s instructions if necessary.