Get a 12-gauge cold-weather extension cord for your block heater.

Yes, you need a specific cord. Normal extension cords turn into brittle wire hangers at -30°C. A block heater pulls 1000–1500 watts—enough to melt a cheap cord’s insulation if it’s undersized.

Look for a cord rated SJTW or SJOW. That letter code means it stays flexible in the cold, and the jacket resists cracking. For length up to 50 feet, 12-gauge copper is the safe bet. 14-gauge might work for a 15-foot run in a garage, but out in the open in extreme cold, go 12. The extra few bucks buy you voltage headroom and less risk of a fire.

Also, make sure the cord ends have a tight seal (some come with boots or molded plugs). Snow and slush love getting into loose connections.

Your truck starting in the morning is worth the extra ten bucks.