1997 Buick Century Owner's Manual - Page 346

I Short TripKity Maintenance Schedule I 54,000 Miles (90 000 km) 0Change engineoil and filter (or every 3 months, whicheveroccurs first). An Emission Control Service. 51,000 Miles (85 000 km) 0Change engine oil and filter (or every 3 months, whichever occursfirst). An Emission Control Service. 0Rotate tires. See "Tire Inspection and Rotation" in the Indexfor proper rotation pattern and additional information. (See footnote +.) DATE MILEAGE ACTUAL SERVICED BY: DATE ACTUAL MILEAGE SERVICED BY: 7-16