Most people still opt for block heaters in cold weather (<-20). They used to be standard on all cars sold in Canada/Alaska. I use mine when a plug is availabl

Most people still opt for block heaters in cold weather (<-20). They used to be standard on all cars sold in Canada/Alaska. I use mine when a plug is available. It keeps the engine oil from thickening, making it easier to crank the engine during start. Imho a battery heater is more effective as it increases the cranking power available to the starter. Many use both.