I agree that healthy skin and coat starts from within. Check the kind of food you are feeding first. Make sure he is not getting treats that you buy in department stores and pet stores. Omega 3's are awesome for the coat. I also agree that the organic virgin cold pressed coconut oil as a great supplement for skin and coat improvements.
Use the best food available to you and add your omega 3's and don't strip the skin and coat with harsh ingredients in your grooming products.
Coconut Oil - Certified Organic Gold Label Virgin Coconut Oil from Tropical Traditions