Cadillac 1998 Eldorado Owner's Manual page 286

The cap is behind a hinged door on the driver's side of
your vehicle.
The fuel door release is
located on console and on
the Remote Keyless Entry
(RKE)
transmitter.
An alternate fuel door
release is located inside of
the trunk on the left hand
side. Pull it to release the
fuel door.
While refueling, hang'the cap by the tether from the
hook on the filler door.
To remove the cap, turn it slowly to the left
(counterclockwise). The cap has a spring in it; if you let
go of the cap too soon, it will spring back to the right.
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