Butters and lotions topically, can clog the pores and make skin conditions worse. What do you bathe him in? (This could be the problem). Now, if he only has a small dry patch, then yes you can put a lubricate on it. You just don't want to cover him entirely. Usually, Oatmeal based, hypoallergic or medicated shampoos are used for various skin conditions. There are many available. Either online or through your Vet. There will be many for just dry skin. Your Vet will sell one and that's probably the easiest way to start. Good luck....I hate skin conditions. :(
Try using baby shampoo and baby powder.