This is what I did on my panhard rod. It was the most seized of seized! Tried heat, held in a proper pipe grip but could tell it would damage the threads continuing this way. What I did was get sum clay and built a bowl just under the thread. Filled it with thread release or Wd40 or similar obvs thread release will work best. The reason I didnt just sit it in thread release is because it may have damaged the bushes, much like it would do with coilovers. Plus you only need to spray in a little bit to fill it.Left it for 2 days and come off a piece of cake! Honestly I was shocked. Once its loosened cover it completely if copper grease, doesnt look pretty but who sees the thread of your coilovers anyway! Dan