2003 Chevrolet TrailBlazer Owner's Manual - Page 338

Turn off the engine and give the oil several minutes to drain back into the oil pan. If you don't, the oil dipstick might not show the actual level. Pull out the dipstick and clean it with a paper towel or cloth, then push it back in all the way. Remove it again, keeping the tip down, and check the level. NOTICE: Don't add too much oil. If your engine has so much oil that the oil level gets above the F mark that shows the proper operating range, your engine could be damaged. When to Add Engine Oil If the oil is at or below the L mark, 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 "Capacities and Specifications" in the Index. The engine oil fill cap is located in the engine compartment toward the passenger's side of the vehicle. See "Engine Compartment Overview" in the Index for more information on location. 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. 6-12