If you are looking for something to re-condition door and window seals, this is ideal;

Einszett Gummi Pflege / Rubber Care Stick - 100ml | eBay

I'm not sure that I would use it on external rubber, such as bump strips along the doors, etc. I use AutoGlym Bumper Care for that;

Autoglym Bumper Care (325ml) | eBay

Hope that helps!!!