Can't remember the brand of the t-stat but it was the same one I had in my '79, I think it was Behr?

I have drained the rad so many times and am not using MB antifreeze, I'll have to get some more.

What is the best way to make sure all the air is gone? I've burped many VW's and I've driven this one for thousands of kilometers and it still runs the same temp, I would think any air would have been burped by now.