Originally Posted by
MetroMPG
In Vancouver you'd be fine with 2 hours, max.
300-400 watts isn't a lot for a block heater. They go up to 1500w.
But you do need to manage it with a timer. Or if you're not on a regular schedule, you can get a remote switch so you can turn it on from inside.
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To keep from driving away with the thing plugged in , loop the extension cord around your driver's mirror when you plug it in.
I've almost pulled away with it plugged in once (didn't have it looped on the mirror :D ), started moving then remembered at the last minute: "Oh @*#&!"