I like my hair. It’s thick, looks nice to me styled or messy, and doesn’t get oily. It’s often assumed I use expensive products in my hair. I don’t. I use nothing but water and that’s why my hair is the way it is.
I believe shampoo is almost universally bad for human hair. The basis for this belief is the observation of what happened to my own hair when I stopped using shampoo and discussions with others about their similar experience. In every case, hair quality improved when shampoo was cut.
Your hair probably gets oily within a short time after your last shower. Observe what happens to your hair when you wash it with shampoo. It’s probably extremely dry compared to the way it was before.
You might think this is a good thing but it’s why your hair gets so oily. Shampoo strips the oils from your hair and your hair overproduces oil in retaliation.
If you wash your hair thoroughly with a comb and water, you achieve the same cleanliness, but you exit the shower with fuller-feeling hair that won’t get over-oily.
Don’t believe me? Use your power of observation and put it to the test. Wash your hair thoroughly with nothing but water and a comb or brush for one week, and come to your own conclusion.