1998 Buick Regal Owner's Manual - Page 184

NOTICE: Do not try to clear frost or other material from the insideof the rear window with razor blade a or anything else that sharp. This may damage is the rear defogger grid and affect your radio's ability to pick up stations clearly. The repairs wouldn't be covered by your warranty. ~ If you choose to add a cellular telephone to your vehicle, and the antenna needs to be attached to the glass, be sure that you do not damage the grid lines forthe AM-FM antenna. There is enough space between the lines to attach a cellular telephone antenna without interfering with radio reception. On cars equipped with the rear window defogger and built-in antenna, the defogger grid serves as a radio antenna. If you have this featureon your car, do not apply aftermarket glass tinting to the back glass. The metallic film in some tinting materials will interfere with or distort the incoming radio reception. Care must be taken when cleaning the rear window because breaks in the resistive material heating element will adversely affect radio performance and defogger performance. See your dealer fordetails. Because this antenna is built intoyour rear window, there is a reduced risk of damage caused by car washes and vandals. 3-32