'Rubber Seals':
The seals on most vehicles are no longer made of natural rubber; vehicle manufacturers use a specialized synthetic material called ethylene propylene diene monomer (EPDM). Real rubber, or blends containing real rubber, just cannot endure the direct exposure to sunlight (ultraviolet light) and the harmful-to-rubber oxidizing gases in our atmosphere.
The soft seals around doors, windows, hood and trunk are constantly being flexed and compressed all the while being subjected to a hostile environment. Use a product that contains Glycerine (Zymol Seal), a natural plant anti-oxidizing agent, it will prolong the useful life of the seal by restoring the original moisture and resist tearing and sticking
JonM