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I'm being transferred from Vancouver to Winnipeg and will soon face my first season of winter driving. My car is equipped with a plug although it's never been used. I know it has to do with keeping the car warm, but I wonder whether it's effective and how often it should be used? – Sita in Vancouver

You're not alone. Folks who've spent their lives on the west coast are often puzzled by the dangling plug on the front of the car.

The prairie provinces receive plenty of sunshine, but in moving east you'll also experience some days (weeks, or months) of extreme cold. That's when a block heater comes in handy.

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"Trying to start an engine in really, really cold weather is hard on the battery, hard on the starter motor, and it's also hard on the engine components themselves because the lubricating oil doesn't get a chance to circulate very effectively until the engine warms up. A block heater helps to alleviate those situations," says Dr. Peter Frise, scientific director of the AUTO21 research network at the University of Windsor.

As long as everything is in good condition – such as the battery and the spark plugs – modern fuel-injected engines will almost always start, despite the temperature outside. However, there's little doubt that starting a car in extreme cold temperatures without using a block heater can result in excessive wear of engine components.

"If you can imagine two pieces of metal that are dry, and the oil is really thick and sitting in the bottom of the engine with a consistency like toothpaste, when the engine starts to crank, the oil pump will have a hard time forcing that oil throughout all the little passages in the engine and lubricating everything. So the first few seconds when the engine starts, those parts will be rubbing on each other without the benefit of lubrication. That makes it harder for the engine to start, but it also means the parts will wear out more quickly," says Frise.

So how often will you need to plug-in, and for how long?

"The amount a block heater is used is largely based on personal preference. As soon as the temperature hits zero, some people plug in their cars, while others – myself included – know you really don't need to do it until the temp reaches minus-20," says Pamela Vernaus, of Manitoba Hydro's Power Smart program in Winnipeg.

"On average, from November through the end of February, we estimate there are about 30 days when you would use a block heater. It's not as cold here as west coast people think it is," says Vernaus.

When the temperature warrants, many motorists plug-in their vehicles the night before heading to work in the morning. However, a University of Saskatchewan study found that running a block heater for more than four hours is a waste of energy. If your unit is not equipped with a timer, invest in one to optimize energy use.

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"If you're not going to use the car, it doesn't matter if it cools down. The key point is warming it before you go to start it. So if you just go into a store to buy groceries, there's no need to plug the car in. If you're going to be in there shopping for four hours and it's really cold, then it might be worth plugging it in. When at home, set the timer so it comes on 90 minutes or a couple of hours before you leave for work in the morning," says Frise.

In addition to protecting your vehicle from excess wear in cold weather, the use of a block heater will lessen the time it takes to warm the interior.

Send your car questions to Joanne Will at globedrive@globeandmail.com

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