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Ask Joanne

Should you warm up your car first, or start it and go? Add to ...

No matter what season it is, I usually just fire up my car and go, though I’ve often wondered if I should let it warm up? – Ella in Toronto

In these modern times most of us don’t think once, never mind twice, about warming up our engines. We turn the key and expect our vehicles to be ready to go. But despite technological advancements, are we compromising performance, or even shortening the life of our vehicles?

From the invention of the automobile until the late 1980s, fuel delivery was regulated by a carburetor – which often required a warm-up period to ensure smooth operation. Modern cars start easier in varying climates than their predecessors because they’re fuel-injected.

Let’s take a moment to think about what happens in an electronic fuel-injected engine when the ignition key is turned. The fuel-injection computer calibrates precisely how much fuel is required. When your car engine is cold, the computer directs the fuel injectors to allow more fuel into the engine. As the engine warms, the injectors let in less fuel.

“You get a lot of old wives tales, and even mechanics will argue amongst themselves. There’s not a definite answer; you can find two mechanics with two different answers,” says veteran mechanic Russ Perry.

“It doesn’t hurt to start and let it warm for a minute or two, or to start and drive away. It comes down to your preferences. If I had a brand-new vehicle I was really proud of, I would want to let it warm up for a minute or so, but that’s more of a psychological thing.

“What I tell my customers when they’ve asked me this question over the years: in ordinary summer, spring, or fall weather – get into your car, start the engine, and while putting on your seat belt, getting comfortable, checking your mirrors and turning on your radio, 30-45 seconds have passed, so put it in gear and off you go,” Perry says.

“People argue that at 32 F or 0 C [freezing], the oil is cold, it’s like molasses, so you should let it warm up – but I’ve never seen oil like molasses when doing oil changes out in my shop, down to -10 C.

“If you’re up in northern Alberta, where it’s -20 or -30, a lot of vehicles are plugged in at night so the battery is kept warm via an electric blanket. They also have a probe that sticks into the oil pan or engine block to keep everything warm. So under extreme conditions, without these devices, yes, you’d want to let it warm up a few minutes because the oil is quite thick,” Perry says.

When I contacted Toyota Canada, its representative said it’s not necessary to warm your vehicle, nor will doing so cause any harm. The rep adds that there are pros and cons: the motor and oil will warm, and the coolant will flow – but idling for long is harder on the environment.

There are a few more things to consider before setting off to a racing start. Beyond making sure your windows are clear and connecting any Sat-Nav or MP3 gadgets, you should monitor the startup lights on your dash. Failure to do so could mean you’ve overlooked a brake malfunction, low oil pressure, or even tire pressure.

Before cranking the engine, put the key in the “on” position. Your indicator lights on the dash will illuminate, accompanied by an audible tone, while the computer checks various sensors. If you watch the dash, your airbag indicator and two or three other lights will cancel. When the tone stops, the engine can be started.

If you have a fuel-injected car, it’s not necessary to warm it up in average weather conditions. If you choose to do so, it may not harm your vehicle – but it could hurt your wallet. There are bylaw fines for idling in many municipalities – including the one-minute rule in Toronto.

E-Mail Ask Joanne at globedrive@globeandmail.com

Our gas is cheap compared to what drivers in the U.K. and the rest of Europe pay to fuel their cars

 

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