Learning how to use a block heater is a rite of passage in Canada. You know you’re in a cold part of the world when you see little plugs dangling from the grilles of every car on the street. Have you ever wondered what those things are? Or exactly how a block heater works? It’s an interesting, yet simple device that has probably saved more engines—and gotten more people to work on time—than any other winter-specific automotive add-on. And if you think modern engines no longer require this accessory, you may change your mind after you’ve experienced a very cold start at minus thirty.
- Difficulty: Easy
- Duration: 10-30 minutes
- How often: As needed
Coolant Is Key
The term block heater is commonly used to refer to these winter warming devices. In reality, most designs feature a freeze plug installed in place of your engine’s expansion plug that serves to actually heat up the coolant that flows through your motor. Even though antifreeze isn’t circulating when the engine is off, the heat from the plug transfers throughout the cooling system via this fluid and slowly covers the entire engine block in a blanket of warmth. In turn, this also keeps the engine’s oil temperature from plummeting to the point of a solid, sticky mess. Note that you can also find magnetic heaters you can just stick on the engine bloc.
Easier Starting, Warmer Cabin
Why is it so important to keep oil and coolant warm in the dead of winter? When learning how to use a block heater, you’ll often hear that thick, cold oil can’t adequately lubricate the inside of your engine and can lead to damage and excessive wear during cold starts.
A block heater keeps the motor just warm enough for the oil to flow properly, which also eliminates resistance from the pistons when they are being turned by the starter. A car that starts quickly is only one positive aspect of using a block heater. Your car’s climate control system uses coolant to warm up the cabin, so it gets nice and toasty that much faster if the vehicle has been plugged in.
When to Plug In?
Wondering how to use this tool most effectively in the winter months? On a modern vehicle, there’s very little need to operate the block heater for more than four hours prior to starting up. This means you can save on electrical costs by using a timer to activate the heater at just the right moment in the wee hours of the morning.
You won’t need to use a block heater all the time—only when the cold weather is at its worst, typically around minus fifteen or lower. And the extra watts you spent will be recovered with a better gas mileage as the engine reaches its optimal temperature quicker. Needless to say, your engine will experience less stress when you start it on a minus‑thirty‑degree morning.