1997 Buick Riviera Owner's Manual - Page 328

I Short Trip/City Maintenance Schedule I 48,000 Miles (80 000 km) 0Change engine oil and filter (or every 3 months, whichever occurs first). An Emission Control Service. 45,000 Miles (75 000 km) 0Change engine oil and filter (or every 3 months, whichever occursfirst). An Emission Control Service. 0Inspect air cleaner filter if you are driving in dusty conditions. Replace filter if necessary. An Emission Control Service. (See footnote"f) 17 Lubricate chassis components (or every 6 months, whichever occursfirst). (See footnote#.) 0Rotate tires. See "Tire Inspection and Rotation" in the Index for proper rotation pattern and additional information. (See footnote+.) ~~ ~ DATE ACTUAL MILEAGE SERVICED BY: DATE ACTUAL MILEAGE SERVICED BY: 7-15