Originally Posted by Mike-in-Orange

For all the rubber seals on the car your two best bets are probably Meguiar's M40 Professional Vinyl & Rubber Cleaner/Conditioner or 303 Protectant. Both are water based products that will keep the rubber seals soft and compliant for many years to come.

Oh, and if anyone ever tells you that silicone is bad for rubber trim and that you should stay away from any "silicone based" products, end the conversation right then and there. They have no idea what they're talking about and their advice should be considered suspect at best.