1997 Buick Riviera Owner's Manual - Page 330

I Short Trip/City Maintenance Schedule I 54,000 Miles (90 000 km) Change engine oil and filter (or every 3 months, whichever occurs first). An Emission Control Service. 51,000 Miles (85 000 km) 0Change engine oil and filter (or every 3 months, whichever occurs first). An Emission Control Service. 0Lubricate chassis components (or every 6 months, whichever occurs first). (See footnote#.) 0Rotate tires. See "Tire Inspection and Rotation'' in the Index for proper rotation pattern and additional information. (See footnote+.) ~~ ACTUAL MILEAGE SERVICED BY: DATE ACTUAL MILEAGE SERVICED BY: 7-17