On my 2000 it's on the bottom drivers side of the radiator, you have to remove the spalsh guard to see it. On the radiator end cap you'll see 2 tabs hanging striaght down with a split in the middle. I used an extra large flat blade screwdriver between the tabs to unscrew the plug. The position of the wires and location of the plug make it difficult to drain into a pan, without making a mess. A small funnel with about a 6 inch hose will help.
The radiator petcock drain on a 1999 Pontiac Bonneville is on the bottom of the radiator. Look for a small black plug that looks like the plug found on a thermos or cooler.
drivers side bottom right of radiator remove shield and look for plug
Look at the bottom or rear of the radiator
Bottom left hand corner of radiator,opposite side of the lower radiator hose.
No
under the radiator, driver side.
Either at the bottom or the rear of the radiator
Look on bottom or rear of radiator
If it is not on the bottom of the radiator, then just remove the lower radiator hose to drain the system.
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.
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.
Should be on the bottom or rear of the radiator or remove the lower radiator hose