Dear Car Talk: In the late ‘50s and early ‘60s, I think I recall seeing cars in southern California with straps hanging down under them, touching the road.
Were these straps really needed, and if so, what was their purpose? And, what changed, because you sure don’t see them anymore. — Paul
Paul: Fads come and go, Paul. Now, instead of hanging strips, we have decals of a kid peeing. The march of progress, right?
The answer is that they really served no purpose on passenger cars. They were decorative. Their purported purpose in the ‘50s and ‘60s was to discharge static electricity that built up in the car, so when you got out and touched the metal door handle or frame, you didn’t set off a 2-inch spark and straighten out your new perm.
But they didn’t do anything. Some people just thought they looked cool, and maybe believed the ad copy on the packaging.
Static electricity does build up in the car — especially when you drag your polyester pants across the seat to get out. But you already have equipment designed to take any static electricity to the ground: your tires.
There was a period, some 20 years or so ago, when manufacturers replaced carbon black, a very conductive material used to stiffen rubber tires, with a different stiffener called silica.
They switched to silica because it created less rolling resistance with the road. If you can make a tire that holds the road well when cornering and stopping but generates less friction when it’s just rolling along, you increase gas mileage.
But silica did a poorer job of discharging electricity, and some customers complained about static shocks. So, manufacturers have adjusted their formulas and now use enough carbon black to allow good static discharge.
But, believe it or not, these straps are still being sold. And somewhere, the bumper strap king’s great grandchildren are sipping margaritas by a pool, enjoying their generational wealth. Along with their neighbor, the inventor of the mood ring.
Dear Car Talk: I own a 2012 Chevy Equinox with a four-cylinder engine. These cars are notorious for oil use.
My car burns oil, but apparently did not meet the oil use requirement for Chevy to replace the defective rings under warranty. Now, with 115,000 miles on the odometer, I am using a quart of oil every 1,000 miles.
Here is what I think: The car’s oil life monitor usually calls for an oil change every 8,000 miles. The car has a 6-quart oil capacity. I am adding 8 quarts of oil between changes. So why should I ever change the oil?
Since the car is burning off old oil and getting a steady supply of fresh oil, I should never have to do an oil change again, right? I am exceeding the manufacturer’s requirement! Is my thinking correct or am I missing the obvious? — Steve
Steve: It’s a good theory, Steve. But, like lots of theories that sound good to their creators, this one doesn’t stand up to scrutiny.
Here’s the part you’re missing: As you burn oil, what you’re leaving behind is the dirt, sludge, carbon and metal fragments that were held in suspension by that oil.
Imagine you chopped up some garlic and put it in a frying pan with some olive oil. When the oil ran low and you started to smell something burning, you pour some more olive oil in the pan.
Now, if you kept doing that for say, 15 days, would the pan be clean? No. That garlic would be “one” with the bottom of the pan, even though you kept adding fresh oil. How do I know that? That’s how my mother cooked.
Anyway, the same sort of thing is happening in your engine. You’re adding fresh oil, but the oil that’s in there is getting more and more concentrated with contaminants.
How do you get rid of that? You change the oil. Drain it out, dirt and all, and replace it with clean oil.
In fact, when you burn oil, it’s even more important to change your oil regularly, just for that reason — so you don’t build up excessive dirt and sludge.
You might even find that you burn less oil after an oil change, Steve, since clean oil doesn’t burn as readily. Try it. And write again if you have any more cooking questions. I’ll be here.
Got a question about cars? Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.
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