What is the best product to use to clean my headlights? They are badly oxidized.

 

Wet sanding with progressively finer sandpaper up to about 2000 grit then polishing, etc.... - that is the hard method. Kits are available to make it easier.

Easy method - but only works well for lenses that are not too far gone. Try some rubbing compound. That will often work wonders on plastic lenses. We use it all the time to restore plastic lenses on emergency vehicle lights.

Afterwards wax them, often. Or they will degrade again much faster.

 

I saw a short YouTube video using toothpaste. I tried it on my Honda headlight lenses and it worked really well.

 

There's a headlight restoration kit available at Autogeek.net Easy to follow instructions.