Do not force the stuck radiator drain plug, because breaking it will likely require radiator replacement. Remove the lower radiator hose to drain the coolant, then flush by running a water hose into the fill port.
The owner of a 2001 Oldsmobile Intrigue with 99,000 miles asked about a tool for the radiator drain while changing antifreeze. The expert said the plug only turns about 90 degrees and may loosen by hand. After the owner reported it was stuck despite using a large screwdriver bit, the expert advised against forcing it because a broken drain usually means replacing the radiator. The recommended method is to remove the lower radiator hose to drain the coolant and flush through the fill port. The owner agreed that was the safest approach.
