I cannot speak for all models, but my 1989 Buick Century has a drainage valve located near the bottom of the radiator on the driver side of the car, and can sometimes require pliers to open. It's usually easiest to look for it from under the car...
Is there a drain plug on a 2005 Buick century
You can find the 1991 Buick Skylark radiator drain plug on the bottom of the radiator. The radiator drain plug will be in the center of the radiator bottom.
where is the drain plug for the radiator on a 1992 buick regal custom
drivers side of radiator on the bottom inside pointing to where driver sits
If you can't find drain plug, just disconnect lower radiator hose.
Look at the bottom or rear of the radiator
The radiator drain plug should be close to the bottom of the radiator facing the engine. It could be a wing nut, or could be the type that is turned by a ratchet and extension.
To drain your radiator, there is a plastic screw or plug on the bottom rght or driver side unscrew an the water should flow out.
Bottom of the oil pan.
There are several drain plugs on that vehicle, radiator (coolant), block (coolant), engine oil, trans oil, etc. There are usually located at the lowest point of that particular system.
Try either the bottom or rear of the radiator--perhaps hidden by lower hose
The Chevrolet Malibu radiator drain plug can be found on the right side of the radiator. The drain plug will be at the bottom of the radiator.