Category Archives: Automotive

Let’s Learn About The Best Time You Should Change Your Oil

If you are one of the many people who let a windshield reminder sticker govern when they get an oil change, here’s our advice to you: Drop that habit. Instead, follow the automaker’s recommended service intervals. In many modern cars, your best bet is to rely on the vehicle’s oil life monitoring system to let you know when it’s time for a change.

Let the Manual Guide You
Oil change information is in the maintenance chapter of your owner’s manual. If for some reason you’ve misplaced your owner’s manual, many automakers have put their manuals online. You can also search our Edmunds Maintenance Schedules. We have an extensive maintenance database on vehicles dating back to l980.

In many instances, you’ll find that the owner’s manual lists two service schedules. These are based on “normal” and “severe” or “special” driving conditions. Read the descriptions carefully to see which schedule reflects how you drive. In our experience, the vast majority of people fall into the normal schedule.

Trust Your Oil Life Monitor
In recent years, a number of automakers have installed oil life monitors of varying complexity in their vehicles. The more basic versions are more maintenance minders than actual systems. They’re based on mileage, and switch on a maintenance light when the vehicle hits a predetermined mileage range.

The more advanced oil life monitors, on the other hand, constantly take information from numerous sensors throughout the vehicle and then use a complex algorithm to predict the life of your oil. Based on your driving conditions and habits, the frequency of your oil changes can vary.

These systems take the guesswork out of knowing when your next service is due. Just drive as you normally would and wait until the maintenance light comes on. You’ll be surprised to see how far a vehicle can go between oil changes. The hardest part is not letting your preconceived notions of oil change intervals second-guess the monitor.

It’s also important to note that these systems are calibrated to work with the factory-recommended oil. They aren’t sophisticated enough to recognize that you’ve upgraded to another blend, so save your money and stick to the factory fill.

Use the Time Estimate
If you have a weekend car or put very low miles on your vehicle, you’ll have to change your maintenance strategy a bit. Robert Sutherland, principal scientist at Pennzoil Passenger Car Engine Lubricants, says that over time, oil becomes contaminated by gases that blow by the pistons, and the longer the oil sits with that contamination, the more it degrades.

Whether an automaker uses an oil life monitor or set mileage intervals, all of them also prescribe a maximum time frame for an oil change. For example, the 2010 Toyota Prius has a recommended oil interval of one year or 10,000 miles — whichever comes first. Since some oil life monitors are more sophisticated than others, the vehicles that employ them will have different time recommendations. You’ll also find this information in your owner’s manual.

Get an Oil Analysis
The issue of what constitutes “normal” versus “severe” driving has long been a point of contention among vehicle owners, mechanics and dealership service departments. All have their own motivations for their recommendations. But the best way to determine how you drive your vehicle is to get your oil analyzed.

An oil analysis will tell you the condition of your oil, and it also can reveal any problems that your engine may be experiencing. Some sample tests can show traces of fuel and coolant in the engine oil, which are early signs of engine problems. When you get your results back from the lab, you’ll also get a recommendation on how much further you can go between oil changes.

Extended-Life Oils: It’s Safe To Switch
Many oil companies are releasing extended-life oils that are guaranteed for the specific mileage listed on the bottle. Mobil’s most advanced fully synthetic product, Mobil 1 Extended Performance, for instance, is guaranteed for 15,000 miles. The company recommends it for vehicles that are beyond their warranty period. This is an important point because many automakers will void your warranty if you do not follow their recommended service intervals.

Owners who change their oil themselves and are looking to extend the time between oil changes can safely switch to a 15,000-mile oil and make a lot fewer trips to the mechanic. They also should switch to a high-mileage oil filter, since the factory filter wasn’t designed for extended intervals.

Tips To Prep Your Car for Long Term Storage

There are a number of times when people need to store a vehicle for an extended period of time. Maybe you have a convertible that you love to drive in the summer, but winter is on the way. Or perhaps you’re going to leave town for a job or an extended vacation. Maybe you are in the military and are being deployed overseas.

Whatever the reason for your time away from the vehicle, you’ll need to put it in storage. If you simply let your vehicle sit on the street or in a garage for an extended period of time, you may return to a dead battery or — worse yet — a damaged engine, ruined tires and a rat’s nest under your hood.

Here are important steps to take before you store a vehicle. They will preserve the life of the engine and ensure that your car starts when you return to it.

Keep It Covered
A garage is the ideal place to store a vehicle. This will protect it from the elements and keep it at a temperature that’s relatively stable. If you don’t have a garage and you can find accommodation at a reasonable price, consider putting the car in a public storage facility.

If you have to leave the car outdoors, consider getting a weatherproof car cover. This will help keep the car clean and dry.

Clean It Up
It may seem counterintuitive to get the car washed when you’re putting it away for months, but it is an easy step and one that shouldn’t be overlooked. Water stains or bird droppings left on the car can damage the paint. Make sure to clean the wheels and undersides of the fenders to get rid of mud, grease or tar. For added protection, give the car a coat of wax.

Change the Oil
Skip this step if you’re only storing the car for a week or two. Consider getting the oil changed if you will be storing the vehicle for longer than 30 days. Ford recommends this in its owner’s manuals, saying that used engine oil has contaminants that could damage the engine.

Top Off the Tank
This is another long-term car storage tip. Fill the tank with gas if you expect the car to be in storage for more than 30 days. This will prevent moisture from accumulating inside the fuel tank and keep the seals from drying out. You should also purchase a fuel stabilizer such as Sta-bil, to prevent ethanol buildup and protect the engine from gum, varnish and rust. The fuel stabilizer will prevent the gas from deteriorating for up to 12 months.

Keep It Charged
An unattended battery will eventually lose its charge. Get someone to start the car every two weeks and drive it for about 15 minutes, if possible. Driving the car periodically has several benefits. It will maintain the battery’s charge, help the car “stretch its legs” and keep the engine and other components properly lubricated. It is also a good idea to run the air-conditioner to keep the parts in working order and the air quality fresh.

If you cannot arrange for someone to start the car, there are two other options. The low-tech solution is to disconnect the negative battery cable. You’ll likely lose the stereo presets, time and other settings. If you want to keep those settings and ensure that your battery starts the moment you return, purchase a battery tender, also known as a trickle charger. This device hooks up to your car battery on one end and plugs into a wall outlet on the other. It delivers just enough electrical power to prevent the battery from discharging.

Don’t Use the Parking Brake
It’s usually a good idea to use the parking brake, but don’t do it when you leave a car in storage. If the brake pads make contact with the rotors for too long, there is a chance that they might fuse. Instead, purchase a tire stopper, also called a chock, to prevent the car from moving.

Prevent Flat Spots
Make sure your tires are inflated to the recommended tire pressure. If a vehicle is left stationary for too long, the tires could develop flat spots as the weight of the vehicle presses down on the tires’ footprints. This process occurs at a faster rate in colder temperatures and with vehicles equipped with performance tires or low-profile tires.

In some cases, simply having someone drive the car for a while will bring the tires up to their normal operating temperature and get rid of any flat spots. In more severe cases, a flat spot can become a permanent part of the tire and it will need to be replaced.

If your car will be in storage for more than 30 days, consider taking the wheels off and placing the car on jack stands at all four corners. This step requires more work, but it can save you from needing a new set of tires. Your tires will be in much better shape when you return if they haven’t had the weight of the vehicle resting on them for a month or more.

Keep Critters Out
A garage will keep your car dry and relatively warm. Unfortunately, those are also two things that make a garaged car attractive to rodents. There are plenty of places in your car for critters to hide, and plenty of things for them to chew on. Try to cover any gaps where a mouse could enter, such as the exhaust pipe or an air intake. Steel wool works well for this. Next, spread mothballs or cotton swabs dipped in peppermint oil along the perimeter of the vehicle. The smell is said to drive mice away.

If you want to take a more proactive approach, lay down a few mousetraps and some rat poison. Just make sure someone can check the garage periodically, in case there are some casualties. Otherwise, you’ll have to deal with a smell much worse than mothballs when you take the car out of storage.

Maintain Insurance
You might be tempted to cancel your auto insurance when your vehicle is in storage. Although that might initially save money, there is a chance that the insurance company will raise your rates due to the gap in coverage, which could cost you more in the long run. This can vary based on where you live and who your provider is, so contact your insurance company to see what options are available to you.

Get Back in Action
Here’s a checklist of what to do when you’re ready to bring your vehicle out of storage:

– Check under the hood for any evidence of rodents. Look for chewed belts, hoses, wires or nests. If you covered the muffler or air intake, remove that material before you start the car.
– Check the windshield wipers to see if the rubber is cracked or brittle.
– Check tire pressure and inflate the tires to the recommended specs.
– Check the brakes. Rust may have accumulated on the rotors. In most cases, this should go away after you drive the vehicle for a short time.
– Check fluids to make sure there have been no leaks and that they are at the recommended levels.
– If the battery cable has been disconnected, make sure that you reconnect it and that the battery terminals are clean.
– Wash your vehicle to remove any dirt that may have accumulated.

More Information About Cheap Gas And Car

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 fuel had 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.

Tips To Change Your Oil

Why change your own oil?

One of the cornerstones of do-it-yourself car maintenance jobs is the home oil change. It’s a simple process that requires few tools, and it’s a sure way to save some money while you avoid the hassle of sitting in a dull waiting room somewhere reading outdated magazines.

More than anything, the basic oil change is a great way to connect with your vehicle and take some control over its maintenance. The time you spend under the hood and under the car affords you an excellent opportunity to look around and see if anything else needs attention.

Tools Required:
Wrench to remove drain plug (box end or socket)
Oil filter wrench
Oil drain pan
Funnel
Latex gloves
Jack and jack stands or ramps (optional, depends on ground clearance)

Materials Required:
Oil
Oil filter
Replacement drain plug washer (depending on application)
Let’s get started.

Steps for changing your oil

– Check the type and amount of oil needed
– Get together your filter, wrenches, and other supplies
– Prepare your vehicle
– Locate the oil filter and drain plug
– Drain the oil
– Tighten the drain plug
– Change the oil filter
– Add the new oil
– Check the oil level
– Check the type and amount of oil needed

Before heading to the auto parts store to buy supplies, consult the owner’s manual to confirm the type and amount of oil that’s required.

The amount is easy. Here, our 2012 Ford Explorer requires 5.7 quarts, so I’ll buy six. Five-quart jugs are tempting because they are cheaper than smaller sizes, but I find them heavy and hard to pour steadily. And a huge container of leftover oil will take up a lot of shelf space.

Make sure to match the oil’s viscosity to your engine. The 2.0-liter Ford EcoBoost requires 5W-30 oil. If I had read the manual carelessly, though, I could easily have brought home 5W-20 instead. That’s the oil specified for the 3.5-liter V6 engine.

Check to see if the manual calls out other specific oil requirements as defined by the by the American Petroleum Institute (API) and the International Lubricant Standardization Approval Committee (ILSAC.) Sometimes synthetic oil is expressly called for. Sometimes it’s not necessary. And sometimes its use is implied by additional requirements.

Get together your filter, wrenches, and other supplies

In addition to oil, you’ll need an oil filter, an oil-filter removal wrench, a wrench to remove the drain plug, a funnel, a drain pan and some gloves. You may also need to raise the car to gain access, in which case you’ll need a floor jack and safety stands, or a pair of purpose-made steel ramps. For this kind of work, never use the flimsy jack that’s supplied with the car.

Yes, my funnel is an empty, dry water bottle with the end cut off. Also, my drain pan has a screw-on lid and pour spout, which makes it easier to transport and recycle the old oil. The only other “tools,” not shown here, are a T-shirt and grubby jeans.

You can buy filters at the dealership or at an auto parts store. Make sure to ask if you’ll need a new drain plug washer. Some dealers automatically include a new washer, if you need one. Others charge extra for it. In this case, I didn’t need a new washer, as you’ll see later.

I like the sort of filter wrench that engages the serrations on the end of the oil filter. Wrenches like that are available at most auto parts stores for a few dollars and they snap onto the end of any common three-eighth-inch-drive ratchet. There are many sizes, but it’s easy to make sure you buy the right one if you match the wrench to the filter right there in the store.

Band-type filter wrenches are more familiar, but they can be frustrating to use if you don’t have enough space — especially if the old filter was over-tightened.

Prepare your vehicle

Your engine and its oil should be warm when you get started, but not hot. Let the car sit so the exhaust system cools off some, but don’t allow things to go stone cold.

If you need to raise the car for better access, this is a good time to do it. Make sure you install proper safety stands, of course. Oftentimes you don’t need to remove tires, but I did it anyway so our photographer, Elon Schoenholz, could have a clear view of things.

If necessary, take off the undercover. Some newer cars have these aerodynamic covers to improve fuel economy and keep things clean. Unfortunately, the covers can hide the engine’s oil drain plug and oil filter. Some covers have built-in access hatches and they’re usually labeled. Sometimes you have to remove the undercover entirely. The good news for us DIYers is that most cars don’t have them. The Explorer does, but it’s held in place with four twist-release clips that don’t require any tools for removal.

Locate the oil filter and drain plug

Now it’s time to locate the oil filter and drain plug. The vast majority of cars have a bottom-mount screw-on filter, such as the one shown here.

In this case, the plug and filter are far apart, meaning I must reposition the drain pan after I drain the oil and before I remove the filter. For this reason, I’m going to completely finish draining and replugging the engine before I work on the filter. If these elements were closer (or if my pan were bigger) I could begin removing the filter while the last of the oil was still dribbling out.

If yours is one of the growing numbers of new cars with a top-mount cartridge filter, the following oil-drain and refill steps are the same, but the filter change process is not. I’ll cover the process for changing a top-mount cartridge filter in another piece.

Drain the oil

With the preliminaries out of the way, it’s time to drain the oil out of the engine. It’s important to place the drain pan under the drain plug — but not directly under it. The angle of the drain plug will cause the oil to stream out at an angle, so I’m offsetting the pan to that side by several inches. If I were doing this outdoors, I would also account for wind. No, really. Those last wispy ribbons of oil can blow around and make a mess.

Remove the oil filler cap. You’ve held your thumb atop a drinking straw filled with water to keep it from running out, right? It’s not quite the same here, because oil would still drain with the oil filler cap on, but it does seem to flow out more smoothly and quickly with the cap removed. If nothing else, taking the cap off now serves as a reminder to put the new oil in before you start the engine.

It’s time to put the gloves on. When you remove the oil drain plug, things start getting messy.

You can usually remove the drain plug with a common end wrench and a bit of muscle. The hex end on a typical drain plug is almost always a common size that comes in a standard tool assortment, but even the domestic carmakers tend to use metric in the 14-17mm range. A three-eighth-inch drive ratchet is perfectly fine, of course, as long as you remind yourself not to use its extra leverage to over-tighten the drain plug when you put it back later.

Go slowly as you remove the drain plug and keep your hands away from the expected path of the oil. It’s going to come out quick and warm. If you miscalculate, it could dribble down your arm. This is another reason why it’s best not to change oil when the engine and its oil are piping hot.

I almost got away clean, but not quite. On the other hand, I usually fumble the drain plug into the pan as the oil comes out. Not this time.

Tighten the drain plug

Inspect and clean the oil drain plug while the rest of the oil is draining. This is where the new drain plug washer would go if one were needed. But as you can see, this one has a permanent O-ring instead. If your drain plug does need a replacement washer, make sure the old one isn’t stuck to the engine’s oil pan — you don’t want to inadvertently stack a new washer atop the old one.
Tighten the drain plug. Theoretically, there is a torque specification for drain plugs, but they’re almost never published in the owner’s manual. Even if you do find the spec, it’s unlikely that the half-inch drive torque wrench you bought to tighten lug nuts will go low enough for this job.

The drain plug is properly tightened if you use the box end of a combination wrench and tighten it as much as you can without using a hammer or slipping a pipe over the wrench for extra leverage. A standard-length three-eighth-inch drive ratchet will work if you choke up on it a bit, but anything longer or larger can lead you down the path of over-tightening. You want the bolt to be tight, but you don’t want to strip it out.

Change the oil filter

Remove the oil filter. New filters that are properly installed don’t go on terribly tight. But they can be hard to get off later because their sealing gaskets swell over time.

Here I’ve added an extension to my ratchet to get a little extra knuckle room. But I’m not going to use the wrench much beyond the point of breaking the filter free. Filters loosen in a hurry, at which point oil starts to gush out all around the perimeter. Go slowly and switch to unscrewing the filter by hand as soon as you can.

Unlike drain plug removal, there is no way to avoid making a mess at this stage. Make sure you reposition the drain pan before you start. Have rags handy and prepare to get some oil down your arm. Don’t let go of the filter once it starts to come off.
Hold the filter over the pan to drain it, but try not to drop it in. It makes a very messy splash.
Use rags to clean as much oil away as you can, paying special attention to the filter sealing surface. Make sure to remove the old filter’s O-ring if it stuck itself to the surface. This rarely happens nowadays, but it’s one of those things you check anyway because a double stack of O-rings won’t seal, allowing your new oil to pump out and ruin your engine.

The last messy step involves smearing a dab of new oil on the new filter’s O-ring.
Install the new filter. At this point I like to take the gloves off so I get a good grip. I’m spinning the filter on gently until the O-ring makes first contact with the sealing surface.
Before I tighten the filter, I draw a reference line on it with a marker or paint pen. Generally, oil filters are tightened no more than three-quarters of a turn to a full turn beyond the point where the O-ring first contacts the sealing surface. Consult your manual or the oil filter box to confirm the proper amount.
Here I’m at three-quarters of a turn with no tools. This is enough. You can go to a full turn if you can manage it by hand, but don’t resort to a filter wrench just because you want to tighten it more than the recommended amount. In most cases you’ll only need a filter wrench for tightening if access is too tight or if your hands are too oily for a solid grip.

Add the new oil

After you reconfirm that the oil drain bolt and filter are both in place and properly tightened, it’s time to add oil. Add approximately one quart less than the recommended amount. Ford’s EcoBoost 2.0 engine requires 5.7 quarts, so I’m adding five now and holding the last one back for later. I also like to hold the bottles on their side for a smooth pour.
Now it’s time to replace the oil cap and start the engine. Run the engine for 30 seconds or so to circulate the new oil, then shut it down and check your work area underneath the car for leaks.
Once you’re satisfied that everything is OK, lower the car off the jack stands or ramps.

Check the oil level

Now that you’re on flat ground, check the oil level. Because I short-filled it slightly, it was no surprise that I had to add a little more oil. As usual, you’ll know the level is full when the oil comes up to the upper hole or hash mark.

The only other step now is to properly dispose of the old oil and filter. Most auto parts stores that sell oil will take your waste oil at no charge. If yours won’t, local municipalities often have household hazardous waste drop-off points.

That’s it. We’re done. Once you’ve done an oil change a couple times and you are familiar with your car’s idiosyncrasies, the whole job takes less than 30 minutes. If you stockpile oil and filters in your garage, you’ll save both time and money compared to going to a mechanic. And once you get comfortable with the basic oil change, a whole slew of other maintenance tasks begin to seem within easy reach.

Know More About Condition of Your Tires

am1In February 2008, 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.

To make matters worse, you might not always find the DOT number on the outer side of the tire. Because of the way a tire is made, it is actually safer for the technician operating the mold to imprint information on the inner side of the tire, so some manufacturers will opt to put the number there. It is still possible to check the DOT code, but you might have to jack the car up to see it. Keep the visibility of the DOT number in mind the next time you are at a tire shop and the installer asks if you want the tires to be mounted with the raised lettering facing in.

That potential inconvenience is going away, however. NHTSA says that the sidewall information about the tire’s date of manufacture, size and other pertinent data is now required to be on both sides of the tire for easier reading.

After checking out a tire’s birth date, give the rubber a visual inspection. Some of the best advice on such an inspection comes from the British Tyre Manufacturers’ Association. It recommends that consumers check tires regularly for any sign of aging, such as tread distortion or large or small hairline cracks in the sidewall. Vibrations or a change in the dynamic properties of the tire could also be an indicator of aging problems, the association says. It recommends replacing the tire immediately if such symptoms appear.

Don’t Buy Used
Tires are expensive, especially when you factor in the price of mounting and balancing. That’s why used tires become more attractive to consumers who are strapped for cash. But the purchase of used tires is very much a buyer-beware situation, Zielinski says. “Even a one-year-old tire can be dangerous if it was poorly maintained,” he says.

When a consumer buys a used tire, he has no idea how well it was maintained or the conditions in which it has been used. The previous owner might have driven it with low pressure. It could have hit curbs repeatedly. It could have been patched for a nail. Further, it’s a dated product.

“You wouldn’t want a used tire for the same reason that you wouldn’t buy a 10-year-old computer,” Zielinski says. “You are denying yourself the advancements in tire technology over the past few years.”

Make Sure You’re Getting a “Fresh” Tire
Just because a tire is unused doesn’t mean it’s new. In a number of instances, consumers have purchased “new” tires at retail stores only to find out later that they were manufactured years earlier. In addition to having a shorter life on the road, a tire that’s supposedly new but is actually old may be past its warranty period.

If you buy tires and soon after discover that they’re actually a few years old, you have the right to request newer ones, Zielinski says. Any reputable store should be willing to make amends. “It is fair for a consumer to expect that ‘new’ is not several years old,” he says.

Letting Go
Getting rid of an unused spare or a tire with good-looking tread may be the hardest thing for a thrifty consumer to do. “Nobody’s going to take a tire that looks like it’s never been used and throw it out,” Kane says. But if it’s old, that’s exactly what the owner should do.

Although Kane has lobbied NHTSA to enact regulations on tire aging, nothing is currently on the books. A NHTSA spokesman says the organization is “continuing to conduct research into the effects of tire aging, and what actions consumers can do to safely monitor their tires when they are on their vehicles.”

It’s too bad that tires don’t have a “sell by” date, like cartons of milk. Since there’s no consensus from government or industry sources, we’ll just say that if your tire has plenty of tread left but is nearing the five-year mark, it’s time to get it inspected for signs of aging.

Of all your vehicle’s components, tires have the greatest effect on the way it handles and brakes. So if the tire store recommends new tires at your five-year check-up, spend the money and don’t put it off. Your life could depend on it.