Replace If Old Everyone would agree that it's common sense to replace a headlight bulb if it's burned out, but did you know that even if your bulbs are still working they should be replaced if they're a few years old? Although today's Halogens perform better and last much longer than the regular incandescent bulbs of yore, they still wear and become dim over time, and the reduced illumination can make it difficult to see clearly at night and in inclement weather
Traditional incandescent lights illuminate by running an electric current through a tungsten filament. The filament is the wire that runs horizontally across the middle of the bulb, and glows when it is lit. Tungsten can withstand high amounts of heat, allowing it to glow when the electrical current gets the filament as hot as 4,600 degrees Fahrenheit.