That's the thing, sometimes they don't start lol. It's usually the battery that dies before the fluids freeze.
Synthetic oils and oils with the 1st number 5W or 0W e.g. 5W30, 0W40, 5W20...stay thin enough and have greater starting power over something with 10W30/10W40. Those are generally 'summertime' oils, which get really thick in the winter. You start the car, and for a few seconds you can hear the bearings knocking against each other due to lack of lubricant. That's why most of the engine wear occurs during startup.
Anti-Freeze is exactly that. They don't freeze. I don't have the chart with me, but I think I recall most 50/50 anti-freeze properly mixed can stand a little colder than -30. Winter Windshield fluid's are often marked down to -25. All the other fluids are basically a form of oil as well.
I find the best way to prevent everything from freezing is to either remove battery, or don't allow the car to stay turned off for more than a day or so...unless you're parked at the airport in which case you're fucked.