Drove all week with petcock (drain plug) 1/2 way in. It would not budge at all! Ordered a new one at Auto Zone for $4. Bought needle long nosed lock pliers. Today I jacked the car up and was ready for combat! Just to see, I put a slip joint plier on that bad boy and was able to snug it all the way! I will NEVER touch that thing again. Have a new one to hang on my garage trophy wall to remind me of all the dumb auto designers out there who give us home mechanics a fit!

Was easily able to take off small hose that goes to heater to drain & refill system with fresh coolant!

Thanks for everyone's help!