I have tried coconut oil in my hair. Doesn't do anything other than when wearing it. I have lots and lots of thick hair. Used to be a bit way, now with age is coarse as hell (especially the lower layers). I'm now using an avocado conditioner/leave on/mask, like for everything made by Garnier. It's pretty good. Will try the overripe avocado mask next.
Use Mane and Tail Shampoo and conditioner. It is a US product made for horses, but is very good for humans. It deep cleans so much hair starts to grow back. The conditioner is superb. Available in one liter bottles about 7 bucks Cdn. You will not regret it.