Category Archives: Automotive

Cars Tires With Nitrogen

A member of the Dodge Challenger owners’ forum was buying a new car from a dealer and noticed green valve-stem caps on all four tires. The salesman told him that the tires had been filled with nitrogen, which would keep the tire pressure and temperature more consistent and that it would prevent tire rot from the inside out. It wasn’t a free add-on, though. The “nitrogen upgrade” was a $69 item on the supplemental window sticker. Another forum member later posted that his dealer was charging $179 for this same “upgrade.”

Some dealerships and tire stores claim that filling your tires with nitrogen will save you money on gas while offering better performance than air. But a closer look reveals that nitrogen has few benefits and much higher costs. For starters, a typical nitrogen fill-up will cost you about $6 per tire.

Why Nitrogen?
The Get Nitrogen Institute Web site says that with nitrogen tire inflation, drivers will note improvements in a vehicle’s handling, fuel efficiency and tire life. All this is achieved through better tire-pressure retention, improved fuel economy and cooler-running tire temperatures, the institute says.

This sounds great in theory but let’s take a closer look at each of those claims.

  • Better tire-pressure retention: Over time, a tire will gradually lose pressure. Changes in temperature will accelerate this. The general rule of thumb is a loss of 1 psi for every 10-degree rise or fall in temperature. The institute says that nitrogen has a more stable pressure, since it has larger molecules than oxygen that are less likely to seep through the permeable tire walls.In 2006, Consumer Reports conducted a year-long study to determine how much air loss was experienced in tires filled with nitrogen versus those filled with air. The results showed that nitrogen did reduce pressure loss over time, but it was only a 1.3 psi difference from air-filled tires. Among 31 pairs of tires, the average loss of air-filled tires was 3.5 psi from the initial 30 psi setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial setting. Nitrogen won the test, but not by a significant margin.
  • Improved fuel economy: The EPA says that under-inflated tires can lower gas mileage by 0.3 percent for every 1 psi drop in pressure of all four tires. The theory is that since nitrogen loses pressure at a slower rate than air, you are more likely to be at the correct psi and therefore get better fuel economy.If you are proactive and check your tire pressure at least once a month, you can offset this difference with free air, and you won’t need expensive nitrogen. We think this invalidates the “better fuel economy with nitrogen” argument.

    For many people, however, this kind of maintenance is easier said than done. Most people either forget to regularly check and top off their tires, or never learned how to do it in the first place. Even Edmunds employees (typically a pretty car-savvy group) were under-inflating or over-inflating their tires, according to a tire-pressure study we conducted a few years ago.

    And though tire-pressure monitoring systems (TPMS) now come standard on cars, a 2009 National Highway Transportation Safety Administration (NHTSA) study found that only 57 percent of vehicles with TPMS had the correct tire pressure. That’s because most systems are only meant to signal that a tire has very low pressure, not to show that the pressure is optimal.

  • Cooler running temperatures: When air is pressurized, the humidity in it condenses to a liquid and collects in the air storage tank you use at the local gas station. When you add compressed air to the tire, the water comes along for the ride. As the tire heats up during driving, that water changes to a gas, which then expands, increasing tire pressure. Because nitrogen is dry, there is no water in the tire to contribute to pressure fluctuations.But this fluctuation in temperature isn’t as significant as you might think. A 2008 ExxonMobil studyplotted the changes in temperature over the course of various inflation pressures. The lines on the graph were virtually on top of each other. In other words, the change in temperature when using nitrogen was negligible.
  • Prevent wheel rot: Nitrogen proponents will also point out that water in a tire can lead to wheel rot. A tire engineer who anonymously maintains Barry’s Tire Tech, a blog on a number of tire issues, says this isn’t really a problem with modern cars.”Alloy wheels don’t really have a problem with water inside the tire,” the engineer writes in a post on nitrogen inflation. “They are coated to keep aluminum from forming aluminum oxide, which forms a crust, which isn’t very attractive. But even then, this crust protects the aluminum from further corrosion from the water.”

    Where wheels have problems is when the aluminum alloy contacts steel, such as the steel spring clip used on wheel weights. It’s a particular issue when salt is present, the engineer writes. “But this problem is totally independent of the inflation gas,” he says. “Steel wheels only have a problem if the paint is damaged.”

How to Repair Your Windshield the Right Way

images-12When faced with replacing a windshield, many car owners default to the lowest-price option. But if you take this route and are in a serious accident, your decision could cost you your life.

An incorrectly installed windshield could pop out in an accident, allowing the roof to cave in and crush the car’s occupants. Furthermore, when the front airbags deploy, they exert a tremendous force on the windshield and will blow out one that is not firmly glued in place.

“There are a lot of schlock operators” installing windshields, says Debra Levy, president of the Auto Glass Safety Council, which offers certification for installers. She says using original manufacturer’s glass is a plus, but choosing a good installer is even more important. To find a certified shop, visit Safewindshields.org and type your ZIP code into the box at the top of the page. Certification is valuable because it keeps installers up to date on advances in adhesives and changing automotive designs.

David Beck, one of two technicians at Windshield Express, near Salt Lake City, installs eight windshields a day and has been working in the auto glass business for 18 years. Beck agrees that certification is important and warns that there are many “tailgaters” — installers with no brick-and-mortar shop — who quickly “slam” windshields into cars with little regard for safety. They don’t handle the windshield correctly, don’t use the proper adhesives and leave the car unsafe for driving and prone to rusting and leaks.

“The thing I wish that drivers knew was that the windshield is the No. 1 safety restraint in your vehicle,” Beck says. The windshield is two sheets of glass held together by an inner layer of strong vinyl. When the windshield breaks, the vinyl holds the glass in place rather than allowing the shards to fall into the car and cut the occupants.

The windshield is a layer of protection that “keeps you inside the car and things out of the car,” Beck says. “This is not the place to cut corners on and go with the cheapest price.”

Steve Mazor, the Auto Club of Southern California’s chief automotive engineer, adds that if the windshield isn’t strong enough and an occupant is thrown from a speeding car, “the odds of survival are much less.” Thirty percent of all fatalities, he says, are due to people being ejected from the car.

An investigation by the ABC News program 20/20 on windshield safety shows technicians incorrectly installing windshields by not wearing gloves. The grease from their hands prevents the adhesives from bonding correctly, Beck explains. Another error that 20/20 caught was technicians failing to use all the necessary bonding agents, such as primer.

When you are looking for a good windshield installer, Levy recommends calling three shops and asking a few qualifying questions beyond just price and certification.

Levy says to ask the shops if they use original equipment glass, which is usually of higher quality and fits better. Also, she suggested asking how long the car should sit after the installation is complete. “If they say you can take the car right away, you should run in the opposite direction,” Levy says. A car should sit at least one hour before being driven and sometimes up to 12 hours, she says.

Beck says if you take your car to a dealership for a windshield replacement, it will just subcontract the job to a glass shop and then mark up the price about 30 percent. He recommends going directly to the glass shop to save money. However, when a car is new, the dealership might be the only place to stock the glass, as was the case for a 2011 Infiniti M56 Edmunds long-term test car where the windshield replacement cost $1,300.

Most windshield installation jobs take only about an hour and can be done at your home or office, Beck says. Once the installer is finished, check for signs that the job was completed correctly. Make sure the molding is straight and that there is no sign of adhesives visible inside the car, Beck says. The car should be clean inside. Debris or dirt left in your car could be the sign of sloppy workmanship, he says.

Should You Change Engine Coolant

For some vehicles, you’re advised to change the coolant every 30,000 miles. For others, changing the coolant isn’t even on the maintenance schedule.

For example, Hyundai says the coolant (what many refer to as “antifreeze”) in most of its models should be replaced after the first 60,000 miles, then every 30,000 miles after that. The interval is every 30,000 miles on some Mercedes-Benz models, but on others it’s 120,000 miles or 12 years. On still other Mercedes, it’s 150,000 miles or 15 years.

Some manufacturers recommend changing the coolant more often on vehicles subjected to “severe service,” such as frequent towing. The schedule for many Chevrolets, though, is to change it at 150,000 miles regardless of how the vehicle is driven.

Many service shops, though — including some at dealerships that sell cars with “lifetime” coolant say you should do it more often than the maintenance schedule recommends, such as every 30,000 or 50,000 miles.

Here’s why: Most vehicles use long-life engine coolant (usually a 50/50 mixture of antifreeze and water) that for several years will provide protection against boiling in hot weather and freezing in cold weather, with little or no maintenance. Modern vehicles also have longer intervals between fluid changes of all types partly because environmental regulators have pressured automakers to reduce the amount of waste fluids that have to be disposed of or recycled.

Coolant can deteriorate over time and should be tested to see if it’s still good, as it can be hard to tell just by appearances. Even if testing shows the cooling and antifreeze protection are still adequate, antifreeze can become more acidic over time and lose its rust-inhibiting properties, causing corrosion.

Corrosion can damage the radiator, water pump, thermostat and other parts of the cooling system, so the coolant in a vehicle with more than about 50,000 miles should be tested periodically. That’s to look for signs of rust and to make sure it has sufficient cooling and boiling protection, even if the cooling system seems to be working properly. It can be checked with test strips that measure acidity, and with a hydrometer that measures freezing and boiling protection.

If the corrosion inhibitors have deteriorated, the coolant should be changed. The cooling system might also need to be flushed to remove contaminants no matter what the maintenance schedule calls for or how many miles are on the odometer. On the other hand, if testing shows the coolant is still doing its job and not allowing corrosion, changing it more often than what the manufacturer recommends could be a waste of money.

Lets know that tires is so dangerous

the owner of a 1998 Ford Explorer in Georgia needed a new tire for his SUV and ended up buying a used one. When he was driving two weeks later, the tread suddenly separated from the tire. The Explorer went out of control and hit a motorcycle, killing its rider. An analysis of the used tire revealed that it was nearly 10 years old.

More recently, an investigation into the cause of the accident that killed the actor Paul Walker revealed that the Porsche Carrera GT in which he was riding had nine-year-old tires. The California Highway Patrol noted that the tires’ age might have compromised their drivability and handling characteristics, according to the Los Angeles Times.

These incidents illustrate not only the potential danger of buying used tires but also the perils of driving on aging tires — including those that have never spent a day on the road.

For years, people have relied on a tire’s tread depth to determine its condition. But the rubber compounds in a tire deteriorate with time, regardless of the condition of the tread. An old tire poses a safety hazard.

For some people, old tires might never be an issue. If you drive a typical number of miles, somewhere around 12,000-15,000 miles annually, a tire’s tread will wear out in three to four years, long before the rubber compound does. But if you only drive 6,000 miles a year, or have a car that you only drive on weekends, aging tires could be an issue. The age warning also applies to spare tires and “new” tires that have never been used but are old.

What Happens to a Tire as It Ages?
Sean Kane, president of Safety Research & Strategies, Inc., compares an aging tire to an old rubber band. “If you take a rubber band that’s been sitting around a long time and stretch it, you will start to see cracks in the rubber,” says Kane, whose organization is involved in research, analysis and advocacy on safety matters for the public and clients including attorneys, engineering firms, supplier companies, media and government.

That’s essentially what happens to a tire that’s put on a vehicle and driven. Cracks in the rubber begin to develop over time. They may appear on the surface and inside the tire as well. This cracking can eventually cause the steel belts in the tread to separate from the rest of the tire. An animation on the Safety Research & Strategies Web site shows how this happens. Improper maintenance and heat accelerate the process.

Every tire that’s on the road long enough will succumb to age. Tires that are rated for higher mileage have “anti-ozinant” chemical compounds built into the rubber that will slow the aging process, but nothing stops the effects of time on rubber, says Doug Gervin, Michelin’s director of product marketing for passenger cars and light trucks.

How Long Does a Tire Last?
Carmakers, tire makers and rubber manufacturers differ in their opinions about the lifespan of a tire. The National Highway Traffic Safety Administration (NHTSA) has no specific guidelines on tire aging and defers to the recommendations of carmakers and tire manufacturers. Carmakers such as Nissan and Mercedes-Benz tell consumers to replace tires six years after their production date, regardless of tread life. Tire manufacturers such as Continental and Michelin say a tire can last up to 10 years, provided you get annual tire inspections after the fifth year.

The Rubber Manufacturers Association says there is no way to put a date on when a tire “expires,” because such factors as heat, storage and conditions of use can dramatically reduce the life of a tire. Here’s more on each of these factors.

Heat: NHTSA research has found that tires age more quickly in warmer climates. NHTSA also found that environmental conditions like exposure to sunlight and coastal climates can hasten the aging process. People who live in warm weather and coastal states should keep this in mind when deciding whether they should retire a tire.

Storage: This applies to spare tires and tires that are sitting in a garage or shop. Consider how a spare tire lives its life. If you own a truck, the spare may be mounted underneath the vehicle, exposed to dirt and the elements.

If your spare is in the trunk, it’s as if it is “baking in a miniature oven,” says Dan Zielinski, senior vice president of public affairs for the Rubber Manufacturers Association. Most often, the spare never sees the light of day. But if the tire has been inflated and mounted on a wheel, it is technically “in service,” even if it’s never been used, Gervin says.

A tire that has not been mounted and is just sitting in a tire shop or your garage will age more slowly than one that has been put into service on a car. But it ages nonetheless.

Conditions of use: This refers to how the tire is treated. Is it properly inflated? Has it hit the curb too many times? Has it ever been repaired for a puncture? Tires on a car that’s only driven on the weekends will have a different aging pattern than those on a car that’s driven daily on the highway. All these factors contribute to how quickly or slowly a tire wears out.

Proper maintenance is the best thing a person can do to ensure a long tire life. Gervin recommends that you maintain proper air pressure in tires, have them rotated regularly and have them routinely inspected.

How To Determine the Age of a Tire
The sidewall of a tire is full of numbers and letters. They all mean something, but deciphering them can be a challenge. This Edmunds article about reading a tire’s sidewall goes into greater detail, but for the purposes of determining the age of a tire, you’ll just need to know its U.S. Department of Transportation (DOT) number.

Tires made after 2000 have a four-digit DOT code. The first two numbers represent the week in which the tire was made. The second two represent the year. A tire with a DOT code of 1109 was made in the 11th week of 2009. Tires with a three-digit code were made prior to 2000 and are trickier to decode. The first two digits still tell you the week, but the third digit tells you the year in the decade that it was created. The hard part is knowing what decade that was. Some tires made in the 1990s (but not all) have a triangle after the DOT code, denoting that decade. But for tires without that, a code of “328” could be from the 32nd week of 1988 — or 1978.

Clearly, these DOT numbers weren’t designed with the consumer in mind. They were originally put on tires to make it easier for NHTSA to recall tires and keep track of their manufacturing date.

Cars Oxygen Sensor

If your car’s “Check Engine” light is glaring at you, it’s probably because the oxygen sensor is malfunctioning. That’s right, the oxygen sensor. It’s a little device that’s a mystery for most drivers but its misbehavior is the problem that most commonly triggers a Check Engine light, according to CarMD.com, which sells an automotive diagnostic tool and provides repair information. The oxygen sensor unseats the formerly most common Check Engine light culprit: a loose gas cap. There are fewer reports of that problem because savvy motorists have learned to fix it themselves and consumers now buy new cars with capless gas tanks.

But don’t despair. Replacing your car oxygen sensor will keep you from wasting money by burning extra gas, and the repair isn’t horribly expensive. We know this firsthand. We had to replace the O2 sensor on our 1996 Lexus ES 300, the subject of our Debt-Free Car project, and it wasn’t as much of a hassle or expense as we had feared.

After the dreaded Check Engine light appeared in our Lexus, we plugged the CarMD device into the car’s computer to read the error code. In our case, the code was P0135, which meant that the oxygen sensor in “bank 1” was malfunctioning. It was surprising to learn that something was wrong with the car, since it still seemed to be running fine.

Even though a car seems to be behaving normally, a faulty oxygen sensor will cause the engine to start “gulping down gas,” says Kristin Brocoff, director of corporate communications for CarMD.com. She says this problem can cause up to a 40 percent reduction in fuel economy. Sure enough, when we checked our fuel record for the driving we did while the Check Engine light was on, our mpg had taken a hit.

The oxygen sensor, developed in the early 1980s, is an essential part of the car’s emissions control system, says John Nielsen, director of engineering and repair for the American Automobile Association (AAA). The sensor is about the size and shape of a spark plug and protrudes into the car engine’s exhaust stream. It determines if there is a lot or a little oxygen in the exhaust, so the engine can make adjustments to the amount of fuel being used in the engine to run at maximum efficiency.

Oxygen sensors in older cars fail for a variety of reasons, according to Bosch, a leading manufacturer of auto components. In some cases, sensors are fouled by gasoline additives or oil from worn engines. Newer oxygen sensors can last 100,000 miles if conditions are right, but often problems occur sooner.

After we plugged CarMD’s diagnostic device into the Lexus’ onboard computer port, we connected it to our desktop computer. It accessed a database of information about this engine code and how to have it repaired. Among other things, the report included an average estimate just to buy a new oxygen sensor: $168.82.

At the first sight of a Check Engine light, most owners of new cars that are still under the factory warranty would simply make a beeline for the dealership’s service bay. But car owners on a budget might want to go the do-it-yourself diagnosis route to save money. By using the CarMD device, or any engine code reader, drivers can learn what the problem is, and the skill level required to fix it, before attempting the task.

Modern cars have two to four oxygen sensors, Nielsen says. A V6 engine, such as the one in our Lexus, has one sensor in each exhaust manifold and one after the catalytic converter. The sensors simply screw into place, but reaching them can be a problem for do-it-yourselfers. Additionally, since the exhaust subjects the sensor to extreme heat, it can “seize” (become frozen in place) and be tough to unscrew. A new sensor comes with anti-seize compound to apply to the threads, but the compound should never be put on the sensor itself.

Nielsen says that while a code reader might indicate that the problem is the car oxygen sensor, there are other problems that can trigger the identical code — a disconnected vacuum hose will do it, for example.

As a first step, a car owner can look under the hood to see if there are any wires or hoses disconnected, Nielsen says. In some cases, a wire leading to the oxygen sensor could be broken or burned out. If nothing obvious is visibly awry, it’s time to go to what Nielsen calls “a trusted mechanic.” Reputable garages use an expensive diagnostic machine called a scan tool — not to be confused with an inexpensive code reader — that can watch the operation of the engine in real time and see if the oxygen sensor is actually the problem.

“Most motorists would be well served to find a shop that they trust and take their car there for all oil changes and tire rotations,” Nielsen suggests. “Then, when they have a problem with something like an oxygen sensor, they trust what the mechanic is saying rather than thinking that they’re trying to rip you off.”

In our case, we learned that the faulty O2 sensor was in the rear of the engine and difficult to reach, so the fix seemed above our skill level. Instead, we took the Lexus to Overseas Garage, in Long Beach, California. There, the mechanic told us that the new sensor would cost $117, plus $144 in labor for a total of $261. This was close to the $246 average cost cited by CarMD’s Brocoff.

While many people opt to simply ignore “Check Engine” lights, Brocoff says this can cause bigger, more costly problems later. “So the problem you could have fixed for a few hundred dollars turns into a repair of the catalytic converter, which would be over a thousand.”

Driving back from the garage, it was a relief not to stare at the glowing check engine light. This made us realize that fixing such a problem provides another benefit: peace of mind.

Tips to Find a Good Car Mechanic

We hear it all the time: “Where can I find a good car mechanic?” In the past, word of mouth was probably the best way to find an auto repair shop that would do the job right and charge a fair price. But now, a good mechanic might be only a few mouse clicks or touchscreen taps away.

Crowdsourced review sites have greatly simplified the search. Here are a few tips on how to work these sites to find a good car mechanic in your area. Keep in mind that this isn’t an exact science. Sometimes a highly rated shop might disappoint, but at least you can tilt the odds in your favor.

Yelp
Yelp.com describes itself as a site that “connects people with great businesses,” whether that’s a hot new restaurant or a top-notch dentist. And, luckily for car owners, it also has auto repair reviews. The site is free and has a mobile version, plus apps for Android and Apple mobile devices.

We’ve had good experiences with Yelp recommendations as we looked for a mechanic to work on Edmunds’ long-term 1996 Lexus ES 300, which is the subject of our Debt-Free Car Project. With our new long-term vehicles, we tend to use dealerships exclusively. But because containing costs is important for the Lexus project, we’ve used Yelp four times to locate independent mechanics. Of the four, we would go back to three of them. We’ve found Yelp to be the most useful site, thanks to its review volume and convenience.

Here are a few tips to help you narrow down your mechanic search. Type “auto repair” into the search field and enter your ZIP code. You can filter the results based on distance, most reviewed and highest rated. The goal should be to find a place that strikes a balance between a good rating and a substantial number of reviews. For example, a place may have a glowing review, but if it’s the only review, that customer’s experience might not be the same as yours. Or worse, it could be a misleading review from an employee or business owner.

Yelp has an algorithm that helps it spot misleading reviews, but sometimes they can slip by undetected. That’s why it is important not to put too much stock in one review. Instead, see what patterns emerge after you’ve read numerous reviews. Look for reviews that are specific and give plenty of details about the users’ experiences.

Sometimes, the owner of an establishment will reply to a review. This response can either be a thank you to someone for a good review or a defense or apology if the review was a negative one. Either way, we consider a thoughtful reply a good sign — particularly in response to a negative review. It shows that the business cares about its reputation.

Angie’s List
Angie’s List prides itself on having a thorough vetting process for its reviews, which cover everything from automotive listings to home repair and even wedding planning. In a search we did for our area, Angie’s List provided a number of repair shops nearby, but we found the volume of reviews lacking when compared to Yelp. For example, one repair shop we used for the Lexus had just one review on Angie’s List, and it was from 2008. The same shop had 22 reviews on Yelp, with the most recent one being less than a month old.

The small number of reviews on Angie’s List can be both a good and a bad thing. On one hand, the chance of a falsified review drops considerably, since the site requires a paid membership to access the site and post a review. But at the same time, it is hard to get a feel for a shop that has very little feedback.

Google
Google’s enormous database will yield the greatest number of search results, but they may require some extra filtering to be useful. Type “auto repair near (your ZIP code)” into the search field. Ignore the sponsored ads at the top of the page. The repair shops will appear about halfway down the page, with their address to the right of their listing. Google has its own review and scoring system. Approach these as you would Yelp reviews.

What is the effect of Cheap Gas

Gasoline is expensive and you’re looking for every way possible to save money at the pump. You already shy away from premium fuel, knowing that your car doesn’t require it. You’d like to save a few pennies per gallon more by going to an off-brand gas station. But you can’t get rid of the nagging fear: Is the cheap gas going to damage your car’s engine?

Edmunds.com put this question to experts in several fields, including an automotive engineer at a major carmaker, gasoline manufacturers and two engineers with the American Automobile Association (AAA). It boils down to this: You can stop worrying about cheap gas. You’re unlikely to hurt your car by using it.

Because of the advances in engine technology, a car’s onboard computer is able to adjust for the inevitable variations in fuel, so most drivers won’t notice a drop off in performance between different brands of fuel, from the most additive-rich gas sold by the major brands to the bare-bones stuff at your corner quickie mart.

Still, spending a few extra pennies per gallon might provide peace of mind to someone who just purchased a new car and wants to keep it as long as possible. People with older cars might not be as concerned about their engine’s longevity. They can buy the less expensive gas and still be OK.

Steve Mazor, chief automotive engineer with the Automobile Club of Southern California, summed it up this way: “Buy the cheapest gas that is closest to you.”

Recipes for Performance — at a Price
But this doesn’t mean that all gas is the same, even though it starts out that way. The fuel from different filling stations comes from a common source: the “base gas” from a refinery. Workers there mix additives mandated by the Environmental Protection Agency into the base gas in order to clean a car’s engine and reduce emissions. Then, the different gas companies — both off-brand and major brands — put their own additive packages in the gas to further boost both cleaning and performance.

A key difference is that the major brands put more additives in their gas and claim to have some secret ingredients. This extra shot of additives provides an additional level of cleaning and protection for your engine.

But is this extra helping of additives, which jacks up the price, really necessary? And, if you don’t use more expensive, extra-additive gas, how soon will your engine’s performance suffer?

“It’s not like any of the fuels are totally junk,” says John Nielsen, director of engineering and repair for the AAA. “If you buy gas from Bob’s Bargain Basement gas station because that’s all that’s available, it won’t hurt your car,” he says.

The real difference is the amount of additives that are in the gas, Nielsen says. More additives essentially afford more protection — but they also cost more.

Some automakers and oil companies believe that the amount of government-required additives isn’t enough to protect engines. They have created a Top Tier gasoline designation. It means that those gasoline brands sell fuels that provide more and better additives.

Nielsen recommends that drivers look in their car’s owner’s manual to see what the carmaker recommends and, when possible, follow that guideline. People who are still concerned about gasoline quality can ask a specific oil company if it has performed independent testing to substantiate its claims.

Selling the Secret Sauce in Gasoline
The major oil companies spend millions of dollars convincing buyers that their gas is superior by creating ads that feature smiling cartoon cars, lab-coated nerds and sooty engine valves. Buy Shell’s nitrogen-enriched gas, for instance, and you won’t get a buildup of “gunk” in your engine, company advertising promises.

Is all this just a marketing gimmick?

“I am a Ph.D. chemist, a nerdy guy who wears a white coat,” says Jim Macias, Shell Oil Company’s fuels marketing manager. “We really believe there are differences in fuels. We can see it, feel it and measure it.”

Macias says the gunk caused by fuels with insufficient additives can foul fuel injectors and even trigger “Check Engine” lights in as few as 10,000 miles.

But not everyone is keen to talk about gasoline quality and whether additives really make the difference.

Edmunds sought comment from one well-known seller of low-price gas: Arco. Arco also often finds itself targeted as being a lower-quality product. BP, Arco’s parent company, did not respond to Edmunds’ interview request.

The American Petroleum Institute provided background comments about fuel additives and promised to provide an expert for an interview. The API spokesman never called back.

Finally, Southwest Research Institute in San Antonio, an independent, nonprofit testing facility, also declined to comment on the question of gasoline quality.

The Skeptics and Their Tests
The Auto Club’s Mazor was more forthcoming, and has some interesting results from a blind test he did on three samples of gasoline from both major and independent gas stations.

“We tested emissions, fuel economy and performance and we could not tell the difference,” he says.

Mazor believes that the driving public has outdated notions about gas. Twenty years ago, only premium fuelhad detergents in it. Back then, it was beneficial to occasionally buy a tank of high-test gas to clean the engine. Then, he says, “regulations were very lax and there was little enforcement. But all that has changed.”

Likewise, Randy Stephens, chief engineer for Toyota’s Avalon, isn’t wholly convinced by the claims of engine protection afforded by higher-priced gas. He says fuel experts at his company study the effects of different brands of gas on the Toyota engines. Automotive engineers disassemble engines after 10,000 miles of running them on different brands of gas to see if there is a difference.