Hello Guest, welcome to the initial stages of our new platform!
You can find some additional information about where we are in the process of migrating the board and setting up our new software here
Thank you for being a part of our community!
Use a fine bristle wire brush and clean the exposed threads as clean as possible and try PB Blaster again, letting it soak for a day. If that doesn't do it, you are looking at heat.
Like Roy said, try a little heat on the fitting.
Ian and I rarely see the kind of corrosion you guys experience back east. The two parts may have become one by now. You may just have to cut it off.