I'll agree with James above. I've treated headlights, fog-lights & tail-lights with Plast-X every 6 months on all my vehicles. This October will be 6 years with the XFire and all of its lights still look like new with no signs of discoloration. Same is true on my 2006 F-150 STX and I've had it 7 years this October.

Now my wife's 2006 VW New Beetle headlights have started getting that haze that's typical. Bought the 3M restoration kit a few weeks back and just need to find the time to spruce up the headlights. Folks claim the 3M kit gives excellent results.