[anonymously]

What is his diagnosis? It might make sense to take him to a dermatologist, especially if this has been going on for a while.
Otherwise, how do you expect people on the internet who may or may not have any veterinary experience and who have not examined your dog or reviewed his medical history to give you any meaningful advice?
Coconut oil and supplements do not help, imo.
PS: Has he had a senior workup? If not, he is due, lab work and some testing could reveal the cause for his dry skin/hair loss condition.

Coconut Oil for Pets?