Yes, and I recommend it in sub-freezing weather. It will keep your water pipes from freezing, within limits. I've done it and was successful in weather in the teens, but would not rely on it for much lower temps.
"Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace." James Madison
'08 34' Classic SO, '12 Ram 2500 4X4, 6.7L Cummins.