1998 Buick Regal Owner's Manual - Page 270

Filling Your Tank The tethered cap is behind a hinged door on the left side of your vehicle. While refueling, let the cap hang by the tether below the fuel fill opening. Gasoline vapor is highly flammable. It burns violently, and that can cause very bad injuries. Don't smoke if you're near gasoline or refueling your vehicle. Keep sparks, flames and smoking materials away from gasoline. 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. 6-6