Where is drain plug on 92 Buick century?

The drain plug on a 1992 Buick Century's oil pan is located on the bottom of the oil pan, which is underneath the engine. To access it, you'll need to get under the car. It's usually a fairly standard bolt, but you'll need a wrench or socket of the correct size (check your owner's manual for specifics). Be aware that the oil will be hot if the engine has recently been running, so allow it to cool down before attempting this.