Don't know why the nuts freeze up on the lower studs that we use to shim the front fenders to align fender/door gaps. This nut is stuck and the double nut method on the stubby end does not work. I have some paraffin that has been lying around and I found a video that demonstrates how easily a stuck fastener breaks free with a little heat and waxing the threads (method #5 of 16 in video). I have a hair dryer, but may have to go down the street to see my buddy with a torch.
