Oldsmobile 1999 Intrigue - Manual (Page 247)

yellow blue
6-7
If your fuel filler door release won’t operate, there is a
manual release tab. The tab is located against the trim on
the driver’s side of the vehicle, in the trunk.
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.