To be sure that no external moisture gets into the Lincoln Navigator Head Light though, it is a prudent idea to silicone seal the edges. Clear silicone sealant can be found in any hardware store (and some auto part stores), and can be applied to the seam along the Navigator headlights where the clear lens meets the rear housing. The $5-$10 is worth it in the long run to protect your investment.
During the first few days of operation, it is normal to see some moisture appear in your Lincoln Navigator Headlights. This is due to the small amounts of moisture in the plastic and coating that are evaporated when the headlights are first warmed up during use. This sort of moisture is normal and should disappear within a few days.
Theoretically you can, but we highly recommend against doing so as it will void the warranty on the Lincoln Navigator Headlights. This is due to the fact that the constant flashing of the halo leads its life to be decreased dramatically. If you are unable to wire the halos to your Navigator's parking lights, we recommend wiring them to your Navigator's low beams or installing a separate switch.
To our knowledge, all of the Sonar (aka Spyder) and KS (aka Anzo) brand headlights we sell are street legal as mandated by federal law in the United States. That means basically that they are designed to the specifications set forth by the DOT (United States Department of Transportation). On occasion, DOT may test models to double check for compliance. In cases where these Lincoln Navigator headlights fail (rare) DOT will have the companies issue a recall. For such headlights, we can take them back and refund you. For other brands, we can not guarantee DOT compliance. Also, please be advised that you may have local laws that may disallow these sorts of headlights to be used.