you can also use silicone grease or vaseline since they both won't perish rubber. I used to use silicone grease, just a very thin coat around the door seals. never had any issues.
depends on what you want to use it on . . I did my petrol flap on the jeep . . and it disintegrated as soon as a drop of fuel hit it.
Truck bed lining . . tough as old boots that stuff