On Mon, 6 Aug 2018 13:59:03 -0700 (PDT), Ed60062
Depending on your definition of "fading out", what you have described
is perfectly normal. The longer wavelengths of AM band signals have
trouble penetrating overpasses and under power lines. Most static is
AM in nature, so AM is highly susceptable to those symptoms. List to
the Steely Dan song "FM". "No static at all" is comparing FM to AM.
Back in the 60's, cars often only had AM radios, so having music other
than elavator music on FM was a huge improvement. You could drive
under power lines without your favorite song fading away.