Should You Start a Car with the Block Heater Plugged In?

If you live in an area that faces colder climates, your vehicle will likely have a block heater. This crucial component requires you to plug it in before you turn on your car in freezing temperatures. However, you may wonder if you can start a car with the block heater plugged in, especially if you have a command start on your vehicle. 

So, is it bad to start your car to warm it up with a block heater plugged in? You can rest easy and know that it is okay. You will not cause any damage or adverse effects to your car by starting your vehicle when the block heater is still plugged into an electrical outlet.  

The Purpose of a Block Heater 

You may ask, what is a block heater, anyhow? A block heater is a necessary component for operating vehicles in cold climates. These heaters will keep the engine block warm even in extreme weather conditions so that the oil remains at a thin consistency for optimal performance. 

If an engine block is too cold, the oil will thicken and not move through the engine as quickly as it should. This thicker oil will need the engine to work harder to run, use more fuel, and increase the emissions it gives. When this situation happens, it will take longer to warm up your vehicle. 

Having a block heater to plug in on your vehicle can reduce the adverse side effects of cold weather on your vehicle’s engine. It can:

  • Help minimize unnecessary wear and tear on your engine 
  • Improve your fuel economy 
  • Reduce the emissions your vehicle makes during operation 

When Should You Plug in a Block Heater? 

If you are unsure when to plug in your block heater, you are not alone. The requirements for using this device are not obvious, especially since many individuals have a personal preference for when they plug theirs in for use. 

As a general rule, anytime the temperatures dip below -20° Celcius or -4° Fahrenheit, you should plug in the block heater on your vehicle. Once the temperature falls this low, the engine oil begins to thicken, so your block heater will help ensure it stays warmer to keep it at a thinner consistency. 

These guidelines are mainly for gasoline vehicles so that others may benefit from a different procedure. For example, automobiles that use diesel fuel may require you to plug them in before the temperatures get that low so they will run at an optimal level. 

How Long Does My Block Heater Need to Work? 

Although many individuals agree that anytime the cold weather becomes extreme, a block heater is necessary, and sometimes drivers will debate the time limit it needs to work correctly. 

For your engine to arrive at the ideal temperature even in colder climates, you should plug in your block heater for four hours. Some car owners will leave their car’s block heater plugged in overnight but may be concerned about the long-term effects. 

Thankfully, you do not have to worry about a vehicle being plugged in for longer than four hours. This way, no one has to run outside in the middle of the night to plug in the block heater for the car engine to be warm to drive to work in the morning. 

Your car engine will not heat any more than it will be once four hours rolls around, though. So if you are concerned about the engine becoming too warm, that will not happen. Any excess heat will dissipate through the cold air once the engine block reaches its ideal temperature. 

What Vehicles Need a Block Heater? 

When it comes to block heaters, where are they used and on which vehicles? As a general rule, any car that you operate in cold climates should have a working block heater. Ideally, diesel engine vehicles will need you to plug in a block heater before gasoline engines require it in low temperatures. 

It does not matter if you are driving a car, truck, or sport utility vehicle. If you live in cold weather, your automobile will most likely need a block heater. 

If you purchase a car from an area with a moderate climate, it may not have a block heater installed. You should ensure you add a block heater if you get a vehicle without one or if you suddenly move to a colder climate. 

Can I Start a Car With a Block Heater Plugged In? 

It is entirely natural to be cautious about starting your vehicle when the block heater is plugged in and working. However, electricity can be a tricky subject and one that some people do not have much background experience in. 

Many car owners who live and work in colder climates will also invest in remote car starters to help warm up their vehicles in extreme temperatures. These after-market devices can make getting into your car a lot more comfortable on a cold morning. 

So, is it safe to start your car with the block heater plugged in from the night before? Yes, there is no reason for you to go outside and unplug it before starting your vehicle. One critical element to remember is that you must unplug your car before getting in and driving away. 

It can be easy to forget about unplugging the block heater when your car is running, and it is a dark winter morning. However, if you drive away with it plugged in, you risk damaging your plug-in, the extension cord, or the block heater connection itself. 

Tips to Not Forget Unplugging Your Block Heater Cord

So you do not forget to unplug your block heater cord each cold morning, there are a few tips you can follow to ensure you will not inadvertently cause damage. 

  • Wrap the extension cord around your side mirror, so you see it when you open your door to drive away.
  • Use an extension cord with a lighted end for visibility on dark mornings. 
  • Use a “Remove Before Flight” flag marker.
  • Purchase an expensive auto-eject device.
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