Diesel Owners: Plug in Your Engine Block Heater Below 20°F

As extreme cold weather hits, many vehicle owners are wondering whether they should use an engine block heater. A first-time owner of a Duramax diesel pickup truck recently asked on TikTok: "At what temperature should I plug in the block heater?" Most commenters suggested that diesel vehicles should consider using a block heater once temperatures drop below freezing (32°F), with more conservative advice recommending plugging it in as soon as temperatures reach 20°F (approximately -6.7°C). Some owners noted that preheating not only reduces engine wear during cold starts but also lowers startup noise in the early morning, showing consideration for neighbors. Experts explain that cold temperatures cause engine oil to thicken and reduce its lubricating effectiveness, while metal components become more brittle and prone to damage. Diesel engines, which rely on high compression and heat for ignition, are especially vulnerable and benefit significantly from preheating. Available preheating options include engine heating blankets, oil pan heaters, and coolant heaters—some of which require professional installation. Owners are advised to choose the most suitable method based on local climate conditions, vehicle type, and personal usage habits.