Headlights should not be left on while the vehicle is not in use. If you are not driving, you will just drain your battery while having your headlights on.
Night time.
All the time
All the time mostly when it is raining or it is dark
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It doesn't corrode and remains shiny.
You can but it makes matters worse. This would be the time to use your fog lights if you have them.
it's an illegal to use a different colored headlights.
In Michigan, you are required to turn on your headlights from half an hour after sunset until half an hour before sunrise. Additionally, you must use your headlights whenever visibility is poor, such as during rain, snow, or fog, when you cannot see more than 500 feet ahead. It's also a good practice to turn on your headlights whenever windshield wipers are in use.
You use low beam headlights when you're in a town or city in any location.
Use your high-beam headlights at night whenever it is legal and safe.
good ones
Good ones.