Try buffing the old lense, first. There are a couple of products now made specifically for cleaning up old plastic lenses, or just use some polishing compound.

Bob

 

You would be better off buffing it, or if it is really bad get some sand paper (1500, 2000, and 2500 grit) and commence polishing. Make sure whichever you do you tape off the car or treat the headlight before you put it on. You could swap lenses but you will be baking your headlights (220 degrees for 8 minutes and pull the lenses off prying them apart with a flat head screw driver; then put the old lens on the new housing with some silicone and bake for another 3 minutes and press the old lens and new housing together).

 

I was watching "Supercars exposed" on Speed channel the other day and one of the commercials was about Diamondite.com... no sanding involved. It did sound fantastic, until I checked the website... $ 60 for the kit
If you're willing to spend that much, you can get by without any baking, swapping, or sanding.

However, Bob is right as I've seen different restoration products (only polishing involved) at AZone or Advance Auto. Typically they run around $ 20. By the time you buy all the different sanding paper grits you spend probably as much as just getting a $ 20 kit.

 

Yeah, it's about $18 for all the sandpaper...but you can polish many more headlights. I have a bunch of sandpaper and a buffing kit I will be using. I will be sure to post results.

 

can someone tell which light bulbs i need for 2001 Audi A6 2.8 one of the low beam (i guess its called) on the right side died so i have to put on the high beams but someone told me its H7? i might as well get me some 10,000K H7 bulbs from ebay correct? By the way SAND its takes like half hour- hour and cheap and makes them like new i did worth every penny and second.

p.s. can someone private message me which type of bulbs i need thx.

 

2 options for cloudy/used/old lens:

First: Take the headlamp apart yourself and clean the lens well. This can be done by using a lady's blow/hair dryer all around the edges of the lens which melts/loosens the black silicone holding the headlamp together, once heated equally all the way around, pull lens off of head lamp assembly, clean, and re-silicone (WELL) to put back together.

2nd Option: Go to your local wal*mart, autozone, advanced auto, pepboys, etc and purchase the headlamp restore kit. You can search the forums for mine and other's write ups about how well it really works. Hope this answers your question.