GMC 1996 Sonoma Owner's Manual page 233

When to Add Oil
If the oil is at or below the ADD line, then you'll need to
add some 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 oil. If your engine has so
much oil that the oil level gets above the
cross-hatched area that shows the proper
operating range, your engine could be damaged.
Just 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.
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