1999 Buick Riviera Owner's Manual - Page 328

yellowblue Long Trip/Highway Scheduled Maintenance 50,000 Miles (83 000 km) (Continued) - When doing frequent trailer towing. - Uses such as found in taxi, police or delivery service. If you do not use your vehicle under any of these conditions, change the fluid and filter at 100,000 miles (166 000 km). j Change engine oil and filter (or every 12 months, whichever occurs first). An Emission Control Service. j Lubricate chassis components (or every 12 months, whichever occurs first). (See footnote #.) j Rotate tires. See "Tire Inspection and Rotation" in the Index for proper rotation pattern and additional information. (See footnote +.) 52,500 Miles (87 500 km) DATE ACTUAL MILEAGE SERVICED BY: j Change engine oil and filter (or every 12 months, whichever occurs first). An Emission Control Service. j Lubricate chassis components (or every 12 months, whichever occurs first). (See footnote #.) 60,000 Miles (100 000 km) DATE ACTUAL MILEAGE SERVICED BY: 7-26