1993 Buick Riviera Owner's Manual - Page 280
1993 Buick Riviera Manual
Page 280 highlights
Explanation of Scheduled Maintenance Services 3. Throttle Body Mounting Bolt Torque" -- Check the torque of the mountingbolts and/or nuts. * An Emission Control Service. The U.S. Environmental ProtectionAgency has determined that the to perform this maintenance item will not nullify failure the emission warranty limit recall liability to thecompletion vehicle or prior of useful life. General Motors, however, urges that all recommended maintenance services performed at the indicated intervals and the maintenance be recorded be in "Section EMaintenanceRecord". 278