Can Magnetic Oil Pan Heater Stay On While Driving Diesel Truck In Winter?

Updated 11/13/2025 | Published 11/04/2025

Question:

Can I use the Heat Magnet on my 3/4-ton diesel truck oil pan all winter, or should I remove it when driving?

asked by: Glen

Expert Reply:

Glen, the Zerostart Heat Magnet # ZE35MR works great for cold starts, but it needs to be removed before you drive. It’s designed as a portable heater for parked equipment - vibration could knock it loose on the road.

When parked, just stick it to a clean, flat steel oil pan, plug it in a few hours before startup, and it’ll keep your oil warm and ready. The built-in thermostat limits surface temps to about 250°F, so it’s safe to leave plugged in overnight.

Do you usually plug in with a timer or just before heading out? That’ll help you get the best use out of it.

expert reply by: Andrew N

Glen

11/13/2025

Got it. I’ll take it off before driving then. Truck’s a ’17 Ram 2500 Cummins, and I park outside all winter. Would it hurt to just leave it plugged in overnight every night?

Andrew N.

11/13/2025

@Glen Nope, not at all - that’s actually the best way to use it. The Zerostart Heat Magnet # ZE35MR has a built-in thermostat that cycles around 250°F surface temp, so it’ll keep your oil warm without overdoing it. Plug it in after dinner and your Cummins will be ready to fire up by morning with a much easier cold crank, which technically won't be a full-on cold crank in the morning!