I regularly clean/treat all of my own vehicle's weather stripping with PB
's Natural Look. Normally works out quite well, but I will tell you after this most recent bout of cold weather...don't do it. It will be a problem. Luckily, we don't see this kind of cold often...like usually more than a decade between occurrences.
I don't know if 1Z
's Gummi Pflege or Tiefenpfleger would be any different. I have both, but NL is what I had on when the cold weather hit.