1998 GMC Sonoma Owner's Manual - Page 262
1998 GMC Sonoma Manual
Page 262 highlights
Checking Engine Oil 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. When to Add Engine 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 "Capacities and Specifications" in the Index. . NOTICE: Don't add too much If your engine has oil. so much oil that the oil level gets above the cross-hatched area that shows the proper operating range, your engine could be damaged. Be sure to f i l l 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