Wiper blades are one of the most neglected components on vehicles today. Many blades are cracked, split, torn, brittle, worn or otherwise in obvious need of replacement. Others may look okay, but do a lousy job of wiping when put to the test.
Ninety percent of all driving decisions are based on a clear unobstructed view of the road, which means good visibility is absolutely essential -- especially during wet weather when vision may be obscured by water, road splash, sleet or snow on the windshield. But good visibility requires wipers that are in good condition. If the wipers are chattering, streaking or otherwise failing to wipe cleanly and consistently, you need new blades -- NOW!
Most experts say wiper blades should be replaced every six to twelve months for optimum performance and driving visibility. That's because wiper blades don't last forever. Natural rubber deteriorates over time. Halogen-hardened rubber as well as synthetic rubber provides longer life. But eventually all blade materials fall victim to environmental factors. Exposure to sunlight and ozone causes the rubber to age, even if the wipers aren't used much.
As a set of blades age, they lose much of their flip-over flexibility and they're less able to wipe cleanly. They may develop a permanent set (called "parked" rubber) or curvature which prevents full contact with the windshield. This tends to be more of a problem on vehicles that are parked outside in the hot sun all day. The sun bakes and hardens the rubber. Then when the wipers are needed, they streak and chatter because they've taken a set and won't follow the curvature of the windshield. It can be very annoying as well as dangerous.
Cold weather can affect blade life, too. Freezing temperatures makes rubber hard and brittle, which increases the tendency to crack and split. The holders can also become clogged with ice and snow, preventing the holder from distributing spring tension evenly over the blade. The blade "freezes up" and leaves streaks as it skips across the glass.
Heavy use can be hard on wiper blades, too, because dust, abrasives, road grime and even bug juice wear away the edge that the blades need to wipe cleanly. As the blade loses its edge (which is precision cut square to maximize the squeegee effect), water gets under the blade and remains on the glass. The result is reduced visibility and poor wiping action.
Any blade that's chattering, streaking or doing a lousy job of wiping, therefore, is a blade that's overdue for replacement. The same goes for any blade that is cracked, torn, nicked or otherwise damaged.

Checking Your Blades

A simple check is to try your windshield washers. If the blades are not in good condition, you'll see why when they attempt to wipe the washer solvent off the glass. Streaking, chattering or any other problems will be clearly obvious.
This test also gives you the opportunity to check your windshield washer system. Do both squirters work? If not, a nozzle may be plugged with dirt or a hose may be kinked or loose. Does the spray hit the windshield where it is supposed to? If not, the nozzles need adjusting. Does the washer pump deliver an adequate stream of solvent? If not, the vehicle may have a weak washer pump, or a clogged, kinked or loose hose. Most washer reservoirs have a screen to filter out debris that could clog or damage the pump. If this screen itself is buried under debris, it can choke off the flow of solvent to the washers.
After you've checked the windshield wipers, check the rear wiper too if your vehicle has a rear wiper system. Many sport utility vehicles, vans, minivans, station wagons, hatchbacks and fastbacks do. After all, it's just as important to see what's behind you when backing up in the rain as it is to see what's ahead. You can use the same test (try the rear windshield washer, if so equipped), or simply spray some water onto the glass with a squeeze bottle and see how the wiper performs.

Other Factors That Affect Your Wipers

How well the wiper blades perform also depends on the condition of the wiper arms and holders. A blade's wiping ability is affected by the amount of spring tension on the wiper arm, the number of pressure points or claws that hold the blade, and the design of the blade itself. If the springs in the arms are weak (which is more apt to be a problem in older vehicles), the wipers may not be pressed against the glass firmly enough to wipe cleanly. Replacing the blades won't make any difference because the problem is weak arms not bad blades.
If the blades can be pulled away from the glass with little resistance, it's time for new arms. Most vehicle manufacturers publish tension specs for their arms. If the arm doesn't meet the spec, it needs to be replaced.
Remember to check the tension on the rear wiper arm, too, because rear wiper arms are often damaged by drive-through car wash rollers.
Wind lift is another factor that can interfere with good wiping action at highway speeds. Many windshields are steeply sloped to improve aerodynamics. But steeply raked windshields with a lot of glass area direct more wind against the wipers. This can lift the blades away from the glass at high speed unless the wiper system and blades are designed to counter the aerodynamic forces. Some blades have specially designed vents and airfoils to minimize lift and/or generate downforce to keep the blades in constant contact with the glass as speed increases. If your original equipment blade holders need to be replaced, be sure the replacements have the same anti-wind lift design.
Another factor to keep in mind is the design of the blade holder. A blade holder needs to distribute the tension of the wiper arm evenly over the blade while also allowing the blade to flex as it follows the changing curvature of the glass. The better quality replacement blade holders typically have six to eight claws to spread the pressure of the wiper arm over the blade. More claws also increases flexibility so the blades don't lose contact at the sides of the glass.

Replacement Blades

You can usually replace wiper blades yourself, and can replace just the blade with a refill or the entire blade assembly. Refills will save you money. If you're installing a blade assembly, most come with some type of adapter to fit the arms on your vehicle. The old blades pull or push off the arm by pressing a release button or pin on the wiper holder.
If you are replacing the blade only with a refill, the old blade can be removed by squeezing the locking tags in at the end of the blade so it will slip out of the holder. Make sure the replacement blade is the same length and claw width as the original. A blade that is too long may create interference problems, while one that is too short may not fit the holder.

For cold weather driving, you might consider installing a set of "winter blades" on your vehicle. These have an enclosed holder that prevents ice and snow from building up and interfering with the wiper's ability to do its job.

You need new shocks (and/or struts) if your original shocks (or struts) are worn out, damaged or leaking. Leaking is easy enough to see (just look for oil or wetness on the outside of the shock or strut) as is damage (broken mount, badly dented housing, etc.). But wear is often more of a subjective thing to judge. There are also instances where the original equipment shocks may not be worn, damaged or leaking, but may not be adequate for the job they're being asked to do. In such cases, upgrading the suspension with stronger, stiffer or some type of special shock (or strut) may be recommended to improve handling, for trailer towing, hauling overloads or other special uses.
Shocks and struts do not require replacing at specific mileage intervals like filters or spark plugs, but they do wear out and eventually have to be replaced. How long a set of original equipment shocks will last is anybody's guess. Some original equipment shocks may be getting weak after only 30,000 or 40,000 miles. Struts usually last upwards of 50,000 or 60,000 miles.
But when exactly a shock or strut needs to be replaced is hard to say. Because the damping characteristics of shocks and struts deteriorate gradually over time, the decline in ride control often passes unnoticed. So by the time to think you need new shocks or struts, it's usually way past the point when they should have been replaced.
One way to evaluate your need for new shocks or struts is to consider how your vehicle has been handling and riding lately. Does it bounce excessively when driving on rough roads or after hitting a bump? Does the nose dip when braking? Does the body roll or sway excessively when cornering or driving in crosswinds? Does the suspension bottom out when backing out of the driveway or when hauling extra passengers or weight?
A "bounce test" is still a valid means of checking the dampening ability of shocks and struts. If the suspension continues to gyrate more than one or two times after rocking and releasing the bumper or body, your shocks or struts are showing their age and need to be replaced.

Why Replace Them?

Weak shocks and struts won't necessarily create a driving hazards if you continue to drive on them, but there are studies that show worn shocks increase the distance it takes to stop a vehicle on a rough surface. Increased body sway due to weak shocks or struts can also increase the risk of skidding on wet or slick surfaces.
Worn shocks and struts also increase suspension wear (though marginally) but can have an effect on tire wear. If the shocks .
The reason why most people decide to have worn shocks or struts replaced, however, is to improve overall ride quality. If you're sick of bouncing and rocking on rough roads, a new set of shocks or struts will firm up your suspension and restore proper ride control.
If you're interested in performance handling, you can upgrade to premium "gas" charged shocks or struts. These are charged with high pressure nitrogen gas to help minimize foaming in the hydraulic fluid inside the shock. This lessens "fade" on rough roads and helps the vehicle maintain better ride control when cornering.
There are also "heavy-duty" replacement shocks and struts that have larger diameter pistons than stock. These too, provide increases resistance for greater control -- but may be a little too harsh for everyday driving. So some shocks have special valving or adjustable valving that allows the amount of resistance to vary.
Another option to consider if you tow a trailer or haul extra cargo are overload or air-assist shocks. Overload shocks have a coil spring around them to increase the load carrying capacity of the suspension (these also tend to ride stiffer than standard replacement shocks). Air-assist shocks have an adjustable air bladder that acts like a spring to carry extra weight. With this type of shock, air can be added on an "as needed" basis when hauling extra weight.

Replacement

Shocks and struts are generally replaced in pairs -- though this isn't absolutely necessary if only one shock or strut is leaking or has suffered damage at a low mileage.
Shocks are a popular do-it-yourself item on most vehicles because they're fairly easy to replace. But struts are not. Most struts require a fair amount of suspension disassembly as What's more, the wheels must usually be realigned after replacing a strut. For this reason, you're probably better off letting a professional replace your struts.

The type specified by the vehicle manufacturer in your owner's manual. For most passenger car and light truck gasoline engines today, it's any oil that meets the American Petroleum Institutes "SH" rating.
As for the viscosity of oil to use, most new engines today require a multiviscosity 5W-30 oil for all-round driving. The lighter 5W-30 oils contain friction reducing additives that help improve fuel economy, and also allow the oil to quickly reach critical upper valvetrain components when a cold engine is first started. Most engine wear occurs immediately after a cold start, so it's important to have oil that is thin enough to circulate easily -- especially at cold temperatures.
For older engines and ones that are driven at sustained highways speeds during hot weather, 10W-30 or 10W-40 is a good choice. Heavier multiviscosity oils such as 20W-40 are for high rpm, high-load applications primarily and are not recommended for cold weather driving.
Straight weight 30W and 40W oils aren't very popular anymore, but some diehards insist on using them. They say the thicker oil holds up better under high temperature (which it does), increases oil pressure and reduces oil consumption in high mileage engines. But straight 30W and 40W oils are too thick for cold weather and may make an engine hard to start. They may also be too thick to provide adequate start-up lubrication to critical upper valvetrain components during cold weather. So switching to a straight 20W oil would be necessary for cold weather driving. Straight 10W oil can also improve cold starting, but is very thin and should only be used in sub-zero climates. A multiviscosity 10W-30 or 10W-40 will provide the same cold starting benefits of a 10W oil and the high temperature protection of a 30W or 40W oil.
For the ultimate in high temperature protection, durability and all-round performance, synthetic oils are the way to go. Unfortunately, most synthetic oils cost up to three times as much as ordinary petroleum-based oils. They cost more because synthetics are manmade rather than refined from petroleum. But this improves their performance in virtually every aspect:

• Superior temperature resistance. Synthetics can safely handle higher operating temperatures without oxidizing (burning) or breaking down. The upper limit for most mineral based oils is about 250 to 300 degrees F. Synthetics can take up to 450 degrees F. or higher. This makes synthetics well-suited for turbo applications as well as high rpm and high output engine applications.
• Better low temperature performance. Synthetics flow freely at subzero temperatures, pouring easily at -40 or -50 degrees F. where ordinary oils turn to molasses. This makes for easier cold starts and provides faster upper valvetrain lubrication during the first critical moments when most engine wear occurs.
• Better engine performance. Synthetics tend to be more slippery than their petroleum-based counterparts, which improves fuel economy, cuts frictional horsepower losses and helps the engine run cooler. The difference isn't great, but it can make a noticeable difference.
• Longer oil change intervals. Because synthetics resist oxidation and viscosity breakdown better than ordinary motor oils, some suppliers say oil change intervals can be safely extended -- in some cases stretched to as much as 25,000 miles. Such claims are justified by the fact that synthetics don't break down or sludge up as fast as ordinary mineral-based oils do in use. CAUTION: For vehicles under warranty, extending the normal change interval is not recommended because failing to follow the OEM's maintenance schedule can void your warranty.
  Synthetics are available in the same grades as ordinary motor oils (5W-30, 5W-20 and 10W-30) as well as "extended" grades such as 15W-50 and even 5W-50.
  There are also lower-cost synthetic "blends" that combine synthetic and petroleum-based oils in the same container. But you can do your own blend to save money by simply substituting a quart or two of synthetic oil for conventional oil when you change oil. Synthetics are compatible with conventional motor oils.
  Who should use a synthetic oil? The premium-priced oil is best for:
  
  • Turbocharged or supercharged engines
  • Performance or high output engines
  • Vehicles used for towing (especially during hot weather)
  • Vehicles that are operated in extremely cold or hot climates
  • Anyone who wants the ultimate in lubrication and protection

The first and most likely indication of a low battery would be a hard starting problem caused by slow cranking. If the battery seems weak or fails to crank your engine normally, it may be low. To find out, you need to check the battery's "state of charge." A battery is nothing more than a chemical storage device for holding electrons until they're needed to crank the engine or run the lights or other electrical accessories on your vehicle. Checking the battery's state of charge will tell you how much juice the battery has available for such purposes. If your battery is low, it needs to be recharged, not only to restore full power, but also to prevent possible damage to the battery. Ordinary automotive

lead-acid storage batteries must be kept at or near full charge to keep the cell plates from becoming "sulfated" (a condition that occurs if the battery is run down and left in a discharged condition for more than a few days). As sulfate builds up, it reduces the battery's ability to hold a charge and supply voltage. Eventually the battery becomes useless and must be replaced.

Checking The State Of Charge

The charge level depends on the concentration of acid inside the battery. The stronger the concentration of acid in the water, the higher the specific gravity of the solution, and the higher the state of charge. On batteries with removable caps, state of charge can be checked with a "hydrometer." Some hydrometers have a calibrated float to measure the specific gravity of the acid solution while others simply have a number of colored balls. On the kind with a calibrated float, a hydrometer reading of 1.265 (corrected for temperature) indicates a fully charged battery, 1.230 indicates a 75% charge, 1.200 indicates a 50% charge, 1.170 indicates a 25% charge, and 1.140 or less indicates a discharged battery. On the kind that use floating balls, the number of balls that float tells you the approximate level of charge. All balls floating would indicate a fully charged battery, no balls floating would indicate a dead or fully discharged battery. Some sealed-top batteries have a built-in hydrometer to indicate charge. The charge indicator only reads one cell, but usually shows the average charge for all battery cells. A green dot means the battery is 75% or more charged and is okay for use or further testing. No dot (a dark indicator) means the battery is low and should be recharged before it is returned to service or tested further. A clear or yellow indicator means the level of electrolyte inside has dropped too low, and the battery should be replaced. On sealed-top batteries that do not have a built-in charge indicator, the state of charge can be determined by checking the battery's base or open circuit voltage with a digital voltmeter or multimeter. This is done by touching the meter leads to the positive and negative battery terminals while the ignition key is off. A reading of 12.66 volts indicates a fully charged battery; 12.45 volts is 75% charged, 12.24 volts is 50% charged, and 12.06 volts is 25% charged.

Recharging The Battery

CAUTION: Do not attempt to recharge a battery with low (or frozen) electrolyte! Doing so risks blowing up the battery if the hydrogen gas inside is ignited by a spark. Your charging system should be capable of recharging the battery if it is not fully discharged. Thirty minutes or so of normal driving should be enough. If your battery is completely dead or extremely low, it should be recharged with a fast or slow charger. This will reduce the risk of overtaxing and damaging your vehicle's charging system. One or both battery cables should be disconnected from the battery prior to charging it with a charger. This will eliminate any risk of damage to your vehicle's electrical system or its onboard electronics.