Correct, #1 in winter (make that hard winter). #1 has less lubricity. With a 24V, I would use an additive, with a 12V I may or may not worry about it.
#1 is only available where it's REALLY cold. They sell "winterized #2" in many parts of the country where #1 would be overkill. Go to the link given if you want more in depth discussion.