Winterizing - Extreme cold winters

swimmer_spe wrote:
So, I am ready to winterize my trail;)er's water system. I have a nice full brass fitting, an air compressor that can be adjusted for 30psi, and an air line.

Now, I know some of you know how to do this, but do you know how to do it for 'extreme' cold winters? We regularly get -30C(-20F) and colder.

For those who have those extreme temperatures over the winter, do you use antifreeze? How?

Not sure what "extreme" temperatures over the winter have to do with this? :h Freezing is freezing so any sustained temps below 0C and water is going to freeze eventually. Some gravity drain and add antifreeze, some blow only, some do both, but you'll never get agreement on which is "best". Do what suits you.