Heating garage for mice and asfs

Hey guys, so we just built and insulated a room in our garage to expand our rodent breeding, what type of heater would you use? I know that the heater won't be needed for long as it's warming up but for next winter I want to be set.

I use an oil filled radiator I got at Walmart to keep the temp in the low 70s in the rat breeding room.

http://www.walmart.com/ip/Pelonis-7-...-Gray/26978260

We use a Eden Pure Quartz heater. Same setup actually, its an insulated room in the garage, it kept temperatures above 75F when it was -5F outside.