All winter, wipers and wiper blades get a workout-only to sit there and bake in the sun when the weather heats up. The fact is, wipers are vital safety equipment: drivers need them and quite rightly will gripe when they’re not working well. So you may as well avoid complaints by checking out your truck’s wipers as part of regular service.

Wiper motors, linkage, and arms are a pretty straightforward mechanical package. Aside from occasional lubrication required by the manufacturer, these components should need nothing but replacement when they don’t work.

Wiper blade elements are another matter. Age and use causes them to deteriorate and degrade in performance. The response is to change them when they need changing.

But when they start to squeak and streak, does that mean your blades are “bad,” or are they still okay for a while?

This is a judgement call, but for minor problems, remember:

o You may be able to rectify squeaky blades by simply flipping them 180 degrees on the arm (if the mounting system allows).

o Streaky blades, on the other hand, might be improved by cleaning them with a good detergent or renewed with a solvent that’s safe for rubber.

For those who want to split hairs, there are performance standards set up by The Maintenance Council of the American Trucking Associations, a group of equipment designers and fleet maintenance specialists who develop, among other things, maintenance guidelines.

TMC’s Recommended Practice 406A-which addresses wiper blade replacement-defines “wipe quality” this way:

“The wiper blade shall clear the entire wipe pattern within one wiping cycle and with only minor streaking or unwiped lines remaining. A rapidly disappearing haze is acceptable. Unwiped areas, aside from minor streaking, are not to occur in the critical primary vision area of the windshield.”

For “durability,” TMC says, “The wiper blade element shall wipe at least 95% of the effective wipe pattern after operating 200 hours.” If the driver feels strongly that the blades need replacing, it’s probably better to do it than to waste time arguing. Of course, frayed or torn blades ought to be replaced without question.

If you keep good records and especially if you’re computerized, you might track wiper blades to see how long they last. If you already do, you’ve probably found that you can go through a set per truck in much less than a year.

If your trucks spend a lot of time in the sun and/or in smoggy areas, ozone damage to rubber can become a problem. Therefore, TMC recommends you buy only blades that meet the American Society for Testing Materials’ ozone rating of “0,” as defined in ASTM’s procedure D-1171.

Ask your supplier if the blades have that rating. In the end, good wiper blades make the world a clearer place.