The 1998 Chevrolet Malibu doesn't have a petcock on the radiator in the traditional sense. Older vehicles used petcocks to drain the coolant. Modern vehicles, like the '98 Malibu, typically drain the coolant through a drain valve located at the bottom of the radiator itself, or sometimes at a lower hose connection. There's no easily accessible valve on the side of the radiator like a petcock.
To drain the coolant, you'll need to consult your owner's manual for the precise location of the drain valve or look underneath the vehicle at the bottom of the radiator. It will likely be a plug or a valve that you can open with a wrench or screwdriver.
