Follow landsvw’s advice and you will never have problems with your car in Illinois. I have use a block heater for over 40 years and have used synthetic oil since Shell introduced the Synarctic in the 70s. Lately have used Mobil 1 in the winter. I did a stint in the far North (Yukon)and used the same aids as landsvw. The interior car warmer (500watts) is a nice gadget; it allows you to get in a semi-warm car without the windows frosted up. In any case, if the car is very cold in the morning (like -20F or colder), let the transmission warm up for a few minutes before driving off.
Your battery condition and oil viscosity are the two most important factors determining whether your car will start.
On all my carts the engine was never a reson for getting rid of the vehicle; it always outlasted the rest of the car!
Don’t know where you live, but I understand really cold weather. At -33F you need thin oil, a really good battery, and an ignition system in near perfecct condition.
My wife used to work in a place where the car had to be parked outside, and there were no block heater plug-ins. We put 0W30 synthetic oil in her car, and the largest battery that would fit in the case. Employees there used to go out at lunch time, run their cars till warm, and hope enough heat stayed in till 5 pm. My wife never bothered. Even with really cold weather (-25 to -30F, she only needed a boost only once and the car has faithfully startred for the last 12 years.
Ever since we got rid of carburetors, and switched to platinum plugs, cars have been very easy to start if well maintained.
I live in ND, and yes I use the right oil, according to the owner’s manual, I keep my cars and trucks in good tune and replace my batteries about every three years. But by using a block heater, my engines warm up faster, start easier. So I still use a block heater, its better for the engine in the long run.
I had a Festiva that started at -48 with no block heater, it would just turn over, the radio forgot all the stations but it started.