what size allen socket
 

What size allen socket is needed to take brake rotors off 86 Euro 500 SE , should I use lock tight when I put new ones on? thanks.....
William Rogers.....

Long term, for doing any significant work on an MB, you are going to need a whole set of allen sockets. At the very least, you will want to have 5,6,7,and 8mm. That said, you can get by in this case with a set of regular 'L' shaped hex keys, which are very inexpensive, and easy to find. If you need more torque, you can add a small pipe, vise grips, adjustable wrench, or light hammer taps. Bet your rotors will use a 6mm, but I have a different model.

You will probably find that the replacement bolt already has threadlock on it. If you reuse an old one, a low-strength threadlock with a high heat rating is the ideal stuff you want here.
Realistically, this bolt is very unlikely to shake loose, however, and the residual threadlock is probably good enough (in my opinion, of course).

Of course, once the wheel is on, this bolt does nothing other than add some small amount of 'balancing ballast'. Otherwise, you could get by without it in a pinch.

Good luck

I would also add a 14mm to the list. Differential drain/refill plugs. Autozone sells a 3 piece set with a 12mm/14mm/17mm. Reasonable price.

And a 10mm..
 

..for the steering wheel and it seems I've used it elsewhere. I bought a set of 5-10 and get an amazing amount of use from them. Now my son wants a set for his freestyle bike since many of his components use allen bolts as well.