Damn Cheap Bolts
 

Well went to replace my t-stat today and gues what the top damn bolt just breaks off...Guess the last person didnt use any anti-seize and the bolt was rusty. Damn I can win for losing.... I tried drilling it and using an extractor but the extractor is twisting and i dont wanna break it off in there cause you cant drill those SOB's very easily.
Any other options before i drill and tap???

The biggest drilled hole, with the biggest extractor is the best you can do.
Also, soak the hell out of it several times with some spray better than WD40. Get at auto parts store.

It's actually more common than you might think, they get really brittle. When I went to remove mine, one of the heads of the bolt was already broken off. Lucky for me, the rest of it was easily removed with my fingers. The other one unthreaded and when I was examining it, it broke in 2 with no effort.