Don’t even use shampoo. Unless you are seriously getting your hair covered in dirt and grease on a daily basis (maybe you should wear a hat) you really don’t need it. You can wash off sweat with just hot water. Your body can naturally regulate its oil production but when you keep ripping the oils off it goes into over drive. The first 2 weeks with shampoo your hair will be really greasy and then your scalp will adjust and get out of panic mode and slow down oil production. You do have to shower your hair with hot or very warm water though to actually clean it so if you are used to cold showers or off grid and hot showers can’t happen then this might not work for you.