Anyone notice that their 1986-1992 Camaro turn signals fill with dust/dirt over time? Here's why: the turn signals were designed with a "vent" in the bottom of them (that also serves as a snap feature for the inner lens) to allow moisture to escape from the lamp when condensation builds up inside the lamp on those cold and/or damp early spring/late fall days (or immediately after washing). The problem is that there is a direct path into the lamp with no barrier preventing contamination from getting into the lamp over time. Contamination enters the lamp when dirt (carried by the high pressure air either pushed up from under the front of the car by the lower air dam or entering the turn signal lamp pocket directly from the front of the car during normal driving) finds its way into the opening on the bottom of the lamp. The best (and least expensive) way of preventing this and ALSO preventing excessive moisture buildup inside the lamp is to place a piece of every day masking tape over the entire opening thereby creating a barrier where none was before. The masking tape doesn't have to create a perfect seal (in-fact, it's better if it doesn't since moisture still needs a path out of the lamp), but serves solely to create a barrier so that not all of the dirt that would otherwise find its way into the lamp does.

 

Here's a close-up of the actual hole in the bottom of the lamp.