I have been changing my own oil ever since I bought my bike because I don't trust the dealer to do it the right way. I just changed my oil last week. When I removed both drain plugs, they were both tight but when I put them back in, the rear plug acted like it was stripped out. It would not tighten down. When I pulled the drain plugs out, there was not any metal particles on the magnets. I did put new crush washers on and it is not cross threaded.
Any ideas on what could have happened or what the fix would be?