Buick 1993 Century Owner's Manual page 13

You will also find a red circle with a slash through it in
this book. This safety symbol means "Don't," "Don't do
this," or "Don't let this happen."
8
Vehicle Damage Warnings
Also, in this book you will find these blue notices:
In the blue notice area, we tell you about, something that
can damage your vehicle. Many times, this damage
would not be covered by your warranty, and it could be
costly. But the notice will tell you what to do to help
avoid the damage.
When you read other manuals, you might see CAUTION
and NOTICE warnings in different colors or in different
words. In this manual, we've used the familiar words and
colors that Buick has used for years.
You'll also see warning labels on
your vehicle. They use
the same colors, and the words CAUTION or NOTICE.