Read the official word of Vortech:

Owners manual has an "important cold weather information" section: http://www.vortechsuperchargers.com/images/94.pdf

Warranty document specifically mentions a cold start-up under 25*F without a heater in the list of things that will invalidate the warranty: http://www.vortechsuperchargers.com/images/92.pdf


Like many other official limitations, I'm sure there's a "buffer zone" built in to their specification. If it seems to start just fine at temps below 25*F, is it causing accelerated wear and tear? It's up to you to decide whether to take the risk, or adhere to the guidelines to ensure warranty coverage.