I have a 76 Nova race car. Its is going to get cold here in a week or so and I have to keep it outside this winter all tarped up. What I did, was pull the rad hose off the water pump and let all the water come out of the rad and block.Put the hose back on and filled it to the top with pure antifreeze. Fired it up for 5 miutes then turned it off and covered it up. I was wondering if this is enough for -25 celsius? Or is there trick like a lighbulb or somekind of heater I could put on the engine for the week or 2 of cold weather? Just nervous about crackin a block...