Your issue may not be a leaking crank seal at all, maybe it's the head gasket, that would explain the white smoke. I think I would inspect the cylinder, make sure it's not damaged, inspect the piston for the same, if all looks good install a new head gasket. I've had a seal go bad, it does display the symptoms you describe but then when you add the antifreeze in the pipe, hmmm, a head gasket would be the least expensive, if you go to the dealer and say you have a bad crank seal, of course they'll replace it and say thank you $$$$$$$please.