(7-yr old 40-gal gas heater)

Our hot water got suddenly very 'rusty' two days ago. Cold water is
clear. I flushed the tank several times, and it still comes out dirty.
The company says to replace the anode rod. The question is, how?

It's threaded into the top of the tank. I've soaked around the head
with PB Blaster, but I doubt that's getting to the threads. Right now,
I'm using a 1/2" breaker bar with an extension pipe, and getting
nothing. I'm reluctant to use heat (acetylene), because, while the
insulation doesn't sustain combustion, it does sort of burn a little.

Any experience/suggestions would be appreciated. In particular, would
it be OK to use heat?

Thanks,
George