What is the best ways to clean auto light lens?

Answer 1

Meguiar's PlastX will clean the yellow discolouration, caused by oxidation. Less than $10, and there is enough for several applicaltions. It took me about 20 minutes to do both of my headlamps. Follow the instructions, it definitely looks better after.
If you sand the lens, you damage the surface, removing the outside layer of plastic, and it will discolour and oxidize faster.

Answer 2

while most plastic polishes are good, they do not perform well on badly discolored or scratched lenses. I suggest going to your local auto paint supplier and purchasing some 2000 grit sand paper. It is extremely fine and will refurbish the worst headlight lenses. It will take a lot of elbow grease unless you use an electric polisher like I do. Also, wet sanding works best with this paper.

Answer 3

at(auto zone) auto parts they sell a kit ,that contains sand paper 1000,2000,3000 grit and plastic polisher with instructions on how to do it.or the cheapest I heard is toothpaste but I haven't tried it before so I will try in a little piece of plastic and see.

Answer 4

Plastic polish.

Answer 5

if a cover/ clean with vinegar/and water? sometimes that works.
Plastic cleaner works but more expensive.
another relief is to buy new ones?

Answer 6

car polish such as NuFinish, with a microfiber ultra fine cloth, because anything else will scratch them

Answer 7

I'd go with Fred's answer....