My hairdresser told me years and years ago (I was a teenager and now am 76) that I could use dish detergent - takes the excess oil out of your hair and now as my hair has gotten a bit drier, I use Argan Oil of Morocco penetrating oil. Love the way it feels, perfect for my old head.
He also told me that if you have oily hair, dish detergent is the best. It has been for all these years and now I look at the products and it just baffles me how many different kinds of shampoo there are - probably all dish detergent. And I buy the inexpensive dish soap besides. I love the Argan oil too (got that at the grocery store) and I have been using it for close to a year now and have only used about 1/4 of the bottle - just a few drops is all you need. I can't afford all that stuff. Mom found the Argan oil and took it to the assisted living home when she went - her clothes and her Argan oil!!!!!!!! Good enough for the Mom, it is good enough for me. She died two years ago. I don't think she needs it now. Her hair felt like silk. Miss ya, Mom. Edie