I live in Winnipeg, which is just a few degrees warmer than antartica in the winter. When my rad cracked one night at -42C, i decided I needed to do something. Too expensive to put a block heater in (it goes in the front of the #3 cylinder). I ended up putting an inline heater into my lower rad hose. I just rebuilt my engine, and I still didn't bother with the block heater - I'm just going with the inline heater.