Rear spoiler strangeness
 

The studs on the rear spoiler seem to be 1/4-20 thread, but when I try the nuts on them that are supposed to be for the rear spoiler (2 different packs!) they go on one turn then stop. I tried to run my 1/4-20 die over the threads but it starts killing the threads too!! Any thoughts what the problem could be? Would they really put metric threads on??

If it´s a OEM-rear spoiler it´s M6 threads for shure.. That´s if it´s like mine.