DL 6540 Rear Axle Nut
 

I recently had issues with the rear axle and its nut on my 2013 DL650A. It turns out that the axle is steel and the axle nut is some other self locking metal. So once you adjust the chain and re-torque the nut ( factory specs ) , you are supposed to put some kind of grease or anti seize on the threads. ( Factory doesn't do this, but dealer suggests it, but if you check the thread galling is a problem on these bikes. ) If you don't you can't loosen or tighten up the nut and you end up having to replace the axle and nut. About a $ 120 dollar cost. If you are in the middle of no where with out heavy tools you won't get the nut off.

So the moral of the story is. Just use the wrenches that come with the bike's tool kit. They are too short and you won't be able to over torque the nut. Put some anti seize on the axle threads the first time you adjust the chain or replace the tire and you should be good to go.