What's Included in a Tuneup?

Actually, there is no such thing as a tuneup in the traditional sense of replacing parts to bring the ignition and fuel systems up to specs for maximum performance and efficiency, and there hasn't been for years.

About the only things left from the traditional tuneup are new spark plugs, which is typically done every 100,000 miles, and replacing the air filter periodically. The federal EPA and Department of Energy say that replacing a clogged air filter will not improve gas mileage but can improve acceleration 6% to 11%. The agencies do not say what benefit can be derived from fresh spark plugs, but computers that control today's engines adjust the air-fuel mixture and spark timing to compensate for wear, such as when the electrodes on spark plugs are worn down.

How Long Do Tires Last?

We would expect at least 50,000 miles from the tires that come with any new vehicle, but tire life depends on so many factors that it's impossible to give anything other than broad guidelines.

Among the factors are the quality of the tire, the treadwear rating, whether it is a performance summer tire or an all-season tire, the type of vehicle it is mounted on and how it is driven. Performance tires may grip like leeches on dry pavement, but they tend to wear out faster than tires with less rolling resistance. If you drive your vehicle like you just stole it that also will wear tires faster. The Tires 101 information in the Cars.com Advice section, found here, will help you sort out the different types of tires and which is best for your driving style.

Does Engine Coolant Go Bad?

Yes, engine coolant does deteriorate over time, but unless something unusual occurs, you probably won't need to change the coolant in most late-model vehicles until 100,000 miles. Older vehicles probably require more frequent coolant replacement, so check your owner's manual to be sure.

Most manufacturers now use extended-life coolant with a recommended change interval of 100,000 miles. That varies based on maintenance schedules for each manufacturer and individual models. Some Subarus, for example, call for coolant replacement after 13 years or 132,500 miles. Many Ford engines say to replace it after the first 100,000 miles and every 50,000 miles thereafter, though heavy-duty applications (such as frequent towing) should have it done more often.

How Often Should You Rotate Your Tires?

A good time to rotate your tires is when you get the oil changed, assuming you do that at least once a year and more often if you drive, say, more than 10,000 miles annually.

Most vehicle manufacturers recommend that the tires be rotated on the same schedule as oil changes. In most cases that means every 7,500 miles or six months, though some have stretched the oil-change interval to 10,000 miles, such as on many Fords, Volkswagens and Toyotas. BMW allows up to 15,000 miles between oil changes, but that is too long to wait to rotate the tires.

Unless you drive fewer than about 7,500 miles per year, you should probably rotate tires every six months or so.

What's a Cabin Air Filter and When Should You Replace It?

The cabin air filter, a feature found on most late-model vehicles, cleans the air that comes into the interior through the heating, ventilation and air conditioning system. It catches dust, pollen and other airborne material that can make riding in a car unpleasant, particularly if you have allergies or other respiratory problems.

Recommendations on when it should be replaced vary by manufacturer — some say every 12,000 or 15,000 miles, others longer — and how often can depend on how much you drive and where. Check the maintenance schedule in your owner's manual. If you drive in heavy traffic in an urban area that has poor air quality, you could need to replace the filter annually or even more often. However, that also could be true in a desert climate where there is a lot of dust.

Can Cheap Gasoline Hurt Your Engine?

First, if anyone knows where to find cheap gas, please let us know. We could use a break from paying close to, or more than, $4 a gallon.

As far as the pump price affecting engine performance or gas mileage, we doubt there is a direct correlation. In fact, the off-brand station that sells for less than the name brands may be pumping gas made by one of the name brands.

That dirty little secret of the retail gasoline business became public knowledge in August 2012 in the Chicago area, northwest Indiana and southern Wisconsin, when oil giant BP recalled more than 2 million gallons of gas contaminated with gunk that was causing cars to run poorly or stall. BP said at the time that most of the gas was delivered to its own stations, but some also was delivered to other brands, found here. Among the other brands were Phillips 66, Speedway and Citgo, as well as retailers such as Meijer, Sam's Club, Road Ranger and Thorntons.

When Do You Need to Replace Your Brakes?

Just as your gas mileage will vary depending on where and how you drive, so it goes with the life of brake pads (or linings), the friction material that gets pressed against a metal disc or drum to stop your vehicle.

If you drive only 8,000 miles a year but it's mainly in a crowded urban area such as Chicago, Boston or Washington, D.C., you will need to replace brake pads more often than someone who drives 28,000 miles a year across the flatlands of Nebraska. You use your brakes a lot more in urban driving than on a rural highway.

Unfortunately, there is no clear-cut schedule that tells you when it's time to replace the brakes, so you need to rely on your ears and the advice of an experienced automotive technician. Most vehicles should have their tires rotated at least every six months, and that is a good time to have the brakes inspected, as well. A mechanic can check the thickness of the pads and the condition of the brake hardware to spot wear.

Do You Really Need to Change Your Oil Every 3,000 Miles?

No, you don't, according to every auto manufacturer we've talked to. The main advocates of the 3,000-mile oil change schedule are those who would profit by it: repair facilities, quick-lube chains and service departments at some new-car dealers.

Years ago it was a good idea to change the oil and filter frequently, but because of advances in engine materials and tighter tolerances, as well as the oil that goes into engines, most manufacturers recommend intervals of 7,500 miles or more.

What Does the Check-Engine Light Mean?

That is a signal that the onboard diagnostics system (or OBD II) has detected a malfunction in the vehicle's emissions, ignition or fuel systems. It could be something as simple as a loose gas cap or something as severe as a faulty catalytic converter, so you shouldn't ignore it. All cars and light trucks have onboard diagnostics that are supposed to detect engine-related problems that affect the emissions control systems.

The check-engine light (typically a yellow or orange outline of an engine with the word "Check") should come on for a few seconds every time you start the engine with other warning lights. If it stays on, that means there is a problem.

How Do You Know When to Replace Your Shocks?

What we call shock absorbers are really "dampers." The springs in a vehicle's suspension absorb bumps and other road shocks by compressing, and the shock absorbers control the amount of bouncing created when the springs rebound.

Several warning signs can tell you when shock absorbers need replacing, such as your car bottoms out over railroad tracks, speed bumps or dips in the road or keeps bouncing well after the fact. Other signs are unusual noises over bumps, excessive body lean in turns or that the front end of the car dives sharply in hard braking. Because shocks wear out gradually, you might get used to a looser, bouncier ride, much like you get used to longer stopping distances as brake pads wear out.