I have a American High Performance trailer and every year I'm running around chasing loose fenders and bolt's on the trailer. Is it just these trailers or all aluminum trailers do this??

Nylocks.

Easier than broken welds on aluminum trailers !

What's that? Never heard of it.

Lock Nuts with nylon inserts.

They work well and if you also use standard BLUE Loctite you should not have this problem.

Have those on there did not know what they were called. I alwas just called them self locking nuts.