Mechanics set the record straight

gsouth · 发表于 2009-12-18 11:09

Auto mechanics hear it all -- folklore, urban legends and Internet advice gone bad. Jim Kerr, a master automotive mechanic in Saskatoon, Sask., and technical editor for CanadianDriver.com, once had a customer ask him to replace the winter air in his tires with summer air (in case you're wondering, air is air -- it never goes stale or out of season).

He's also heard of people pouring boiling water over a battery to warm it in cold weather (you need to heat it the inside of the battery, not the outer shell) and using a pair of pantyhose in place of a fan belt (he's tried -- it doesn't work.)

Often these myths originate from well-intentioned but just-plain-wrong advice passed down from an older generation. "Cars used to be a lot simpler to work on," says Kerr. "People used to tinker under the hoods all the time. Now cars are a lot more sophisticated and people aren't even sure where to go under the hood in many cases."

Sometimes, there is a small element of truth to these motoring myths but technology has evolved to make the advice outdated. "In a lot of cases, these myths are based on things that people had to do with the technology at the time," says David Armour, president of the Canadian Automobile Association. So, while your dad may have had to pump the gas before starting the car in cold weather, fuel-injected engines mean you just turn the key and go today.

What's the problem?

Perhaps you're trying to cut down on costs by taking the DIY approach to car maintenance. Or maybe your next door neighbour, the self-professed expert mechanic who's never had any training, swears that premium grade gas is better for your car (only if your car manual says it's needed) and permanent antifreeze never needs replacing (permanent in this case only means longer-lasting.) If these scenarios sound familiar, just be sure you know the risks of heeding unskilled advice.

"If you're doing something you don't need to do, it's going to cost you money," says Armour. For example, washing your car with dish soap or laundry detergent will wreck the paint job. "There's also the safety issue," he adds. If you don't maintain your car according to its specifications, parts can wear out faster or even fail entirely.

So read on to find out the truth behind some common auto myths.

1. You need to warm your car before starting out in cold weather: FALSE.
Idling isn't an effective way to warm up your car in the winter -- driving away is. Today's engine and fluid technology is designed to start working as soon as you turn the key (or at lease once your windshield is defrosted). Not only does idling waste gas and cause pollution, it can actually cause damage to your vehicle.

If you're faced with severe winter conditions, you may want to consider a block heater, which warms the engine, or a battery warmer. A battery loses power as the temperature goes down, so warming it gives it that extra boost.

2. All-season tires are as good as winter tires: FALSE.
In the old days, winter tires were knobby things with coarse textured treads. You'd put them on the back two wheels of your rear-wheel-drive car and they would help get you started. Today's high-tech snow tires offer greater control, stability and braking capabilities, so putting winter tires on all four wheels gives you more control when starting, stopping and taking corners.

"Winter tires for ice and snow performance are far superior than all-seasons," says Ralph Warner, director of operations of the Rubber Association of Canada. "With the new rubber technologies and compounds, winter tire compounds have a much better gripping capability in colder temperatures."

3. Restarting your engine is harder on the engine and uses more fuel than idling: FALSE.
Starting and stopping your engine has little impact on the starter motor or battery of today's vehicles. "Today's cars have pretty strong starters and good electrical systems," says Armour. "We need to think of gas mileage and the environment."

According to Natural Resources Canada, or NRC, component wear caused by restarting is estimated to add $10 per year to the cost of driving -- far less than what sitting still costs you in gas. In fact, the NRC recommends that if you're going to be stopped for 10 seconds or longer (except in traffic), it's best to turn your car off. Ten seconds of idling can use more fuel than turning off the engine and restarting it.

4. Filling your tires with nitrogen is better than using plain air: MAYBE.
Some studies have shown that filling your tires with nitrogen reduces gas consumption and improves tire life by maintaining an even tire pressure. Nitrogen molecules are larger than oxygen molecules so they don't leak through the tire walls as readily. Underinflated tires wear out faster, cost more money in gas and are a safety hazard.

But this added convenience will cost you between $5 and $10 to have each tire filled with nitrogen. Not every service station offers nitrogen and topping up with air negates the benefits.

So unless you're a racecar driver, you might want to stick to old-fashioned air. "I think it's one of those unnecessary things," says Kerr. "Spend your money on it if you really want to keep your tire pressure accurate. You're better off buying a good gauge."

Use that gauge to check your tire pressure once a month and keep tires filled according to the optimum pressure (not the maximum, which is the number found on the sidewall of the tire).

Treating your car right

To keep your car in tip-top shape, go to the real experts. "Talk to your service manager at the dealership or a good mechanic at a garage," says Kerr. Don't be afraid to ask questions as to what you should be doing or doing differently.

Ask them, "If it was your mother's car, what would you really have to do to make it safe to drive?" And keep the pantyhose in the lingerie drawer.

长短亭 · 发表于 2015-9-23 18:49

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mont1 · 发表于 2015-9-23 19:34

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