Old Headlights Can Be Dangerously Dim, Study Finds
By Patrick Olsen
December 11, 2018
A report from AAA shows that drivers should pay more attention to cloudy headlights and get them restored.
As your car gets older, its headlights may be giving you far less visibility than you think, according to a new study.
Over time, the plastic coating on headlights can become so clouded or yellowed that they give off only 20 percent of the light they had when you first bought the car, the AAA study says. That puts drivers at great risk of crashes as their car ages.
The findings reinforce the idea that car owners should routinely check the coating on their headlights and, if necessary, get them restored. (See tips on how to do that below.) There are inexpensive kits you can use, or have a repair shop take care of it.
The auto safety group studied the impact that deterioration can have on the amount of light a headlight produces as sunlight breaks down protective plastic coatings. AAA lab-tested headlights from two popular sedans about 11 years in age. Those results were measured against new headlights to quantify the amount of light produced.
Depending on where and how the vehicle is used, headlights can begin showing signs of deterioration in as little as three years to five years, AAA says.
“Driving at night with headlights that produce only 20 percent of the light they did when new, which is already subpar, is a risk drivers shouldn’t take,” says Greg Brannon, AAA’s director of automotive engineering and industry relations, “especially when there are convenient and inexpensive solutions that can dramatically improve lighting performance.”
Drivers need a minimum of 300 to 350 feet to see, react, and brake for something ahead when traveling at 60 mph, says Jennifer Stockburger, director of operations at CR's Auto Test Center.
In CR's tests of new-car headlights, the light reaches 300 feet ahead on average, she says. If the illumination drops to only 20 percent of where it started, that would let drivers see only 60 feet in front of their car.
“Our headlight tests show that even many new headlights tested under ideal conditions for visibility—on clear, moonless nights—don’t produce enough forward light for a driver to see, react, and brake for anything ahead from all but the slowest speeds,” Stockburger says. “If weather or clouded lenses restrict the amount of light output further, night driving becomes riskier than it already is.”
In CR’s experience, some makes and models seem to be more susceptible than others to clouding over. It depends on the size, angle, and composition of the lens and whether the car is garaged or spends its life parked on the street. The effects can vary from just a slight haze to making lenses almost opaque.
Consumer Reports tested a batch of headlight restoration kits in 2016. We found that for less than $25, even very old lens covers could be made clear again, even if only for a year or so.
These products vary in price, ease of use, and effectiveness. Some require power tools, while others just need a fair bit of elbow grease. All take less than an hour to apply. Our testing has found that they can make a big difference, particularly if owners don't rush the job. And old headlamps can be restored for far less money than it would take to replace them.
We tested these restoration kits on dozens of headlights and found that even the poorest performer of the bunch could significantly improve light output depending on how badly the lenses were weathered.
A year later, we found many of the tested lenses had begun to haze over again. A local body shop says it's common for them to refinish lenses annually for customers, confirming that restoration isn't necessarily a long-term fix.
How to Keep Headlights Bright
We discovered several tips while evaluating these products:
Examine your headlight lenses closely before purchasing any of these restoration kits. If they appear clear, don't use a lens restoration product. They are abrasive and can easily damage lenses that don't need such severe restoration.
Before using any restoration kit, it's a good idea to watch the manufacturer's instructional videos online.
If the lenses are clear but the lights appear to be dimmer than they used to be, you may need new bulbs. All bulbs dim over time and should be replaced after a few years.
Regularly clean your lenses with a household glass cleaner. Even a simple cleaning can make a big difference in how well you can see, especially if you live in an area with a lot of snow, ice, or road salt.