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Does My Car Need a Block Heater During Winter?

What is a block heater and how does it work exactly? How many amps does a block heater draw and much does one cost? When is the right time to use it, particularly on a diesel powered vehicle? Here’s a closer look, including some other block heater benefits you likely didn’t know about.

What is a block heater?

Imagine the heating coil on a stove: you turn on the power, the coil glows red, and you proceed to cook up some delicious stovetop popcorn or an omelette.

Now imagine this same heating coil, but smaller—using a single loop of heating element about the size of your thumb, with a plug or bolt at the base, and an electrical connector behind that, the whole assembly is about the size of a small lightbulb.

Congratulations: you’ve now visualized a block heater, effectively a heating element installed to a specific location on your engine block where it’s submerged within the plumbing system used to route liquid coolant around inside of your engine. 

How does a block heater work?

Plug in your block heater, and its heating element continuously warms the liquid coolant inside of your engine’s plumbing, causing warm fluid to circulate. That warm fluid heats up your engine block, and the fluids and hardware inside of it. 

Plugging in a block heater on bathes insides of your engine with warm liquid all night long, ensures it’ll be limber and loose in the morning, ready to fire up much more easily than if left to freeze through overnight.

A block heater isn’t the only way to help keep your engine warm and toasty. Other solutions may include an in-line coolant heater (a heating element installed to your car’s radiator plumbing), or an oil-pan heater (a glue-on warming blanket fixed to the oil pan beneath your engine). 

Each of these devices have the same job of applying heat to an otherwise frozen engine, but you’ll find the block heater is the most common solution in most circles.

Curious how long you should warm up your car during a cold, winter morning? Read our article here, also sharing tips on how to warm up your car’s interior faster.

How many amps does a block heater draw 

By the way, plugging in your block heater will draw about 6 or 7 amps of current. You should continuously inspect all electrical cable insulation, prongs and connectors for signs of damage, wear, or charring for maximum safety.

So, does your car really need a block heater? The answer is ‘maybe’

If you frequently encounter extreme cold in the winter, or live in a particularly northern part of the country, you’re more likely to need a block heater. In the far north, some drivers even install multiple block heaters to their engines, like putting on an extra heated blanket on the coldest nights.

These shoppers know they need a block heater. 

Making a gasoline engine fire up at forty below is extremely difficult but today’s automotive engineers have got it pretty figured out. In fact, the latest synthetic engine oil technology and direct fuel injection systems found in modern engines make life easier on your engine, even when starting from frozen on the very coldest mornings.

If you’re running a properly maintained modern car with synthetic oil, quality fuel and a healthy battery that’s been tested in the fall before the cold weather sets in, chances are even less likely that you’ll need a block heater.

Point is, a block heater can be a nice thing to have, but it can be overkill in a lot of applications.  Of course, you only need to use it when required.

When to use a block heater on a diesel engine

Older cars and trucks may be more difficult to start in cold temperatures, and benefit further from the use of a block heater. When should you use your block heater? Your car will tend to inform your decision over time, but in general, from about 15 to 20 degrees Celsius below zero is a good place to start, whether you’re using a gas or diesel engine.  

Based on years of real-life testing, it’s very rare to see a modern diesel engine that won’t start up, unassisted, even at 25 below. With a gas engine, that drops to about 35 below for new vehicles. 

By about 40 below, gas engines tend to begin to struggle, and diesels may or may not turn over. Your writer’s personal 2019 Volkswagen starts reliably at 40 below, after a little convincing and theatrics at times, and it doesn’t have a block heater. 

How much does a block heater cost?

Most vehicles can have a block heater installed at any point in their life, and the heater itself will run $80 - $150 for most mainstream models, with installation usually taking an hour or so at your local shop’s rate. As a ballpark, expect a bill of $175 to $300 for parts and labour to have the block heater professionally installed. 

Though a block heater can be a powerful weapon in your winter-busting arsenal, don’t underestimate the importance of a quality synthetic engine oil, and a healthy battery, for maximum cold-start confidence on the coldest days of the year.

Other benefits of using a block heater

There are other benefits to block heater use, even if your engine can fire up just fine without one. For instance, a block heater makes life easier on your car’s battery, which will have to expend less juice to turn the pre-warmed engine over. 

A block heater pre-heats the same engine coolant used to heat the interior of your car, so using one means your cabin will warm much more quickly.

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