1994 Buick Century Owner's Manual - Page 267

Selecting the Right Schedule First you'll need to decide which of the schedules is two right for your vehicle. Here's how to decide which schedule to follow: The engineis at low speed most of the time (as in in door-to-door delivery, or stop-and-go traffic). You operate your vehicle in dusty areas. Youtow a trailer. If any one(or more) of these is true your driving, for follow Schedule I. Schedule I Is any one these true for your vehicle? of Most trips are less than 4 miles (6 km). 0 Most trips are less than 10 miles (16km) when outside temperatures are below fi-eezing. Schedule I1 Follow ScheduleI1 only if none of the above conditions is true.