When should I change my headlights?
The front headlights of a vehicle generally last 6 to 8 years: the more time goes on, the less transparent they become (the window becomes opaque), which stops the light from passing through.
If after changing your bulbs and after cleaning your headlights, you feel they are less effective and they light the road less well than they did before, it is time to change them!
Other things to look out for: has the headlight cover turned yellow or opaque and stained despite cleaning, or is the plastic cracked? It's time to change them so you can go back to having the best possible lighting, and good visibility in any situation.