Just like your muscles get stiff in the cold, the fluids in your engine become “stiff” as they thicken. These thicker fluids need to warm up to flow through your engine efficiently. In extremely cold weather (usually defined as below -15 ˚C), your alternator may drain more energy from the battery than usual to start the car, and if this happens often enough, you may find yourself with a drained battery.
Let’s review what engine block heaters and battery blankets are, how they work, and which vehicles they benefit the most to help you decide whether you need one.
What Is an Engine Block Heater?
Winter weather can take a toll on your vehicle, especially because low temperatures make it more difficult for the fluids to lubricate your car and protect its components from damage.
An engine block heater—also known as a car block heater—keeps your engine warm so fluids maintain consistency even when temperatures fall below freezing. Engine block heaters ease cold start strain and reduce wear by warming the engine and keeping it lubricated.
You can plug an engine block heater into any standard 110 V outlet to heat the engine and its fluids, including the oil and coolant. This device won’t warm your car’s interior, but heating the engine helps circulate warm air inside faster once you start.
Types of Engine Block Heaters
Originally, engine block heaters were literal block heaters that were bolted onto the engine block or used in place of a freeze plug to keep the engine warm. Today, you have more block heater alternatives to choose from. Below, we’ll cover the ones that are easy to install. (You’ll find information on block heaters requiring more advanced DIY skills here.)
Dipstick Heater
Instead of your usual dipstick, you can use a dipstick heater to help keep your engine warm. It’s quite simple to install and can easily be switched between vehicles. However, to warm your engine, most block heaters use 750 to 1,500 watts of electricity. A dipstick heater, however, uses only 90 watts.
Oil Pan Heater
Another common car block heater is the oil pan heater. These are often magnetic and can be attached to any metal component around your car’s engine block.
An oil pan heater should be plugged in for two or three hours before you start your car. Don’t leave it running for longer than four hours.
Heater Pads
A silicone heater pad can also keep your engine warm through the winter. Simply plug it in and wrap it around your engine block for a few hours before driving.
Battery Blankets
A battery blanket can protect your battery from damage caused by frigid temperatures. Similar to an engine heater pad, this device is wrapped around the car’s battery to insulate it and maintain a stable temperature. It prevents the battery’s fluids from freezing, allowing you to start your car faster.
Battery blankets are designed for continuous use and can be safely left plugged in overnight or during extended periods of cold weather. When using a battery blanket, wrap it securely around your battery and plug it into a standard 110 V outlet whenever temperatures drop below -15°C.
You can use the blanket alongside your block heater: while the block heater warms your engine and oil, the battery blanket ensures your battery has enough power to start your vehicle.
Battery blankets are compatible with both conventional lead-acid and AGM batteries. Just remember to check for proper clearance if your battery sits inside a plastic battery box, and regularly inspect cords for any signs of wear or damage from road salt exposure.
When to Use a Block Heater or Battery Blanket
Modern vehicles typically have low-viscosity engine oil (e.g., 5W-20) and therefore won’t benefit as much from a block heater. They can handle temperatures—sometimes as low as -30 ˚C—and use engine warming technology. Idling for only 30 seconds before driving may be sufficient to lubricate your engine.
Engine block heaters are most useful for older cars that use 5W-30 or 10W-30 engine oil. If you’ve had your car for several years, or it’s had engine issues in the past, it may benefit from a little extra warmth in the winter.
If you’re still concerned about your engine temperature or want to avoid idling, there’s no harm in using a block heater or battery blanket on super cold days. If you decide to use one, note that these devices are most useful when the temperature drops below -15 ˚C.
The Easy Way to Choose
Searching any website for an engine block heater or battery blanket can lead to unending confusion. That’s why we offer specialized search on our website. Simply enter your vehicle’s details in the top left corner to see items that are guaranteed to fit.
For more information about engine block heaters and battery blankets, visit your local NAPA Auto Parts storeto chat with an expert.
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