Someone on this forum long ago told me not to use some Armour All type products as they contain silicon which dries out the vinyl and causes cracks. Not sure how true this is, but from that point on I've been periodically applying Neopol and I haven't had any cracking in the vinyl of my cars since I've had them over the last 7 years or so.
Neopol is available from your local supermarket, usually.
Neopol All Purpose Creme Polish 300ml | Kitchen, Dining & Household | New World