Buick 2004 Century Owner's Manual page 220

While refueling, let the fuel cap hang by the tether
below the fuel fill opening.
5-8
CAUTION:
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If you spill fuel and then something ignites it,
you could be badly burned. Fuel can spray
out on you if you open the fuel cap too
quickly. This spray can happen if your tank is
nearly full, and is more likely in hot weather.
Open the fuel cap slowly and wait for any
"hiss" noise to stop. Then unscrew the cap all
the way.
Be careful not to spill fuel. Do not top off or overfill the
fuel tank. Wait a few seconds after filling the fuel
tank before removing the fuel pump nozzle. Clean fuel
from painted surfaces as soon as possible. See
Cleaning the Outside of Your Vehicle on page 5-91.