1997 Chevrolet Astro Owner's Manual - Page 268

When to Add Oil If the oil is at or below the ADD line, then you'll need to add at least one quart of oil. But you must use the right kind. This part explains what kind of oil to use. For crankcase capacity, see "Capacitiesand Specifications'' in the Index. What Kind of Oil to Use Oils recommended for your vehicle can be identified by looking for the "Starburst" symbol. Thissymbol indicates that the oil has been certified by the American Petroleum Institute (APT). Do not use any oil which does not carry this Starburst symbol. If you change your own oil, be sure you use oil that has the Starburst symbol on the front of the oil container. ~ NOTICE: ~ Don't add too much oil. your engine has If so much oil that the oil level gets above the cross-hatched area that shows the proper operating range,your engine couldbe damaged. Be sure to fill it enough to put the level somewhere in the proper operating range. Push the dipstick all the way back in when you're through. If you have your oil changed for you, be sure the oil put into your engine is American Petroleum Institute certified for gasoline engines. You should also use the proper viscosity oil for your vehicle, as shown in the following chart: 6-12