How cold before need to winterize?

[Road King Cole]

Here is probably my wrong answer, take it for what its worth.

I keep anti-freeze running in mine, the only "freezable" water would be in the heat exchanger in which should be mostly drained, or I believe you could manually drain it as well.

I would think the temp would have to go well below freezing for awhile to cause problems with what little water is in the system, that is assuming you have anti-freeze in the cooling system.

Mine went below freezing last year before I winterized it and it was fine...

rkc