After you break it loose, spray some penetrating oil on the base of the plug (PB Blaster works good) and work the plug back and forth so the oil can lubricate the threads and minimize any thread damage…Since aluminum expands MUCH more than steel when hot, I would not be afraid to break it loose when hot, but remember to lube the threads on the way out. If you feel resistance coming out, screw it back in and try again…