1993 Pontiac Trans Sport Owner's Manual - Page 230

Engine Oil Additives When to Change Engine Oil Engine Block Heater (omoN) An engine block heater be a big can help ifyou have topark outside in very cold weather,0"F (-18"C) or colder. If your vehicle has this option, see the Index under Engine Block Heater. See if any one of these is true foryou: Don't add anything to your oil. Your Pontiac dealer is ready to advise if you Most tripsare less than4 miles (6 km). think something should be added. It's below freezing outside most and trips are less than10 miles (16 km). The engine is at low speed most of the time (as in door-to-door delivery,or in stop-and-go traffic). You tow a trailer often. Most trips are through dusty places. If any one of these is true for your vehicle, then you need to chahge your oil and filter every 3,000 miles (5 O00 km) or 3 months-whichever comes first. If none of them is true, change the oil every 7,500 miles (12500 km) or 12 months-whichever comes first. Change the filter at the first change and at oil every other oil change after that. 2ES