GMC 1995 Safari Owner's Manual page 211

While refueling, hang
the cap inside the fuel
door.
To take off the cap, turn it slowly to the left (counterclockwise).
Be careful not to spill gasoline. Clean gasoline from painted surfaces as
soon as possible. See "Cleaning the Outside of Your Vehicle" in the Index.
When you put the cap back on, turn it to the right until you hear a clicking
noise.
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