Highgroove, If you are looking for a cheap rubber softener ,good old household bleach is just as good ,and in fact was used by most drag racers to commence burnouts, Oil of wintergreen is also a softener,as long as you dont mind smelling like a football change room.In some countrys tire softeners like Formula Vee traction treatment are banned and are in fact checked by digital "sniffers" touching the tires.The reason antifreeze is used as aleak stopper it is because ethylene glycol is more "searching" than say water,congeals in any holes and prevents the loss of air ??