I might try the star washer, but I'm not sure that will help.
I doubt that most have ever seen a stock pipe separated from the mounting bracket...the "insert" that the bolt threads into in the pipe is recessed inside the pipe, so I don't think the star washer can get a grip on the threaded part that's turning. As for the Green Loctite, I'm not familiar with it, other than seeing it on the package of Blue. Pretty sure I did not see the Green on the parts shelf at the auto supply house.
