High quality rawhide for drums consists of fat, elastin and collagen. Processed properly, it has all the elements necessary for a great sound and long life.
Oils and conditioners can be over applied easily. A natural skin drum head can be saturated to the point of sounding flabby, dead and difficult to tune.
We always recommend allowing the natural oils from hands to condition the skin. In the case of very dry hands, a very light application of environmentally friendly vegetable oil like canola will work annually. Apply with a very soft cloth, and wipe off.
Relieving some tension when not in use will extend the life of the skin.