1993 Buick Regal Owner's Manual - Page 271

Selecting the Right Schedule First you'll need to decidewhich of the two schedules is right for your vehicle. Here's how to decide which schedule to follow: 0 The engine is at low speed most of the time (as in door-to-door delivery, or in stop-and-go traffic). You operate your vehicle in dusty areas. You tow a trailer. If any one (or more)of these is true for your driving, follow Schedule I. Schedule I Is any oneof these true foryour vehicle? Most trips are less than 4 miles (6 km). Most trips are less than 10 miles (16 km) when outside temperaturesare below freezing. Schedule I1 Follow Schedule I1 only if none of the above conditions is true. 269