Originally Posted by Ganglin
Before you buy new ones.. maybe - get a Mothers Power Ball and a bottle of headlight cleaner and try cleaning them. That works on the old plastic rock guards. If they clean up don't use any cleaner with ammonia or alcohol on them in the future - that causes plastic to yellow...
Once the ceiling light lenses turn yellow, they are done.
It is usually caused by cigarette smoking, and/or cooking smoke.
You can soak the lenses in Clorox, for a month and it won't help.