Yes, I know that's true. Regarding oncoming headlight observations, I've recently noticed far more "headlights out" than ever before. These would seem to be mainly halogen lamps with burned filaments, not high-tech light emitters. Now, I am not sure if the failure to replace dead sealed beam units is due to economic reasons or what, but I've also recently seen updated sealed-beam designs with MTBF of only a few hundred hours. Up here in northern latitudes headlights are needed much of the time in winter and no wonder they don't last long in calendar time! Conversely, my pickup has had the same old-tech sealed-beam bulbs for well over 10 years and may be dimming a bit now.
"Always-on" headlights burn out quicker.
I think sealed beams were mostly phased out by the late 1980s, when the “aero” compound-reflector lights became commonplace. Older cars with sealed beams can deliver more light by splicing in a relay circuit, which allows the bulbs to run on full battery voltage. Older vehicles tended to run the full lighting system current through the light switch, not the best design. Look at Painless Wiring and some others for a relay and wiring kit that’s easy to install.
Conversely, my pickup has had the same old-tech sealed-beam bulbs for well over 10 years and may be dimming a bit now.
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Sealed beams do dim over time ,, but you can get replacements for standard round and rectangular sealed beams that take H4 bulbs from many sources (I like Hella) ,, the better quality glass in a more precise shape along with a far superior reflector will be like night and day for you.
You see many headlights burned out for many reasons...
1.) the polycarbonate lenses develop micro cracks from UV and water intrudes.
2.) the water intrusion destroys the reflector and corrodes the bulb contacts reducing voltage to the bulb.
3.) The bulb sockets and the seams where the clear polycarbonate connects to the reflector often leak also.
4.) the polycarbonate deteriorates and becomes cloudy or yellowed trapping excess heat inside the headlight reducing bulb life and light output.
5.) when people replace their headlight bulbs they often touch the glass portion with their fingers. the skin oils greatly reduce the bulbs life.
The answer is to replace your headlights with quality glass lensed units if they are available... If you must keep those crappy polycarbonate units then clean them... here’s how to do it..
1.) get an orbital polisher with multiple speeds and terry cloth bonnets.
2.) depending on the damage use 800 grit / 1200 / 1500 grit paper to get the yellow off.. stop when you get white “sawdust” ,, use a circular pattern , keep the paper wet and go lightly.
3.) use generous amounts of “Meguires PlastX polish” or equivalent with your polisher ,, use medium speed , high speed may melt the lense...