Originally Posted by JeepIdiot
well I know how "it works" lol but I mean, I need to have a nearby outlet at all times when it is parked? is there a switch to turn it on/off?
You will have to size the outlet and extension cord based on the distance to, and wattage of, the block heater. Usually a 20 AMP is required but the cord wire size depends on the length and wattage. There is a built-in preset thermostat in the heater so, except for wasting electricity, you can just plug it in and forget it. The engine coolant temperature will only be maintained thirty some degrees above ambient once the thermostat allows the element to heat.
With the advent of synthetic oil, these are now more of a convenience than a necessity. Heated seats and windshields will warm things up quicker, and the DEF is still going to freeze anyway.