Make one.
Take a 9/32 socket (most sets have them and very rarely used) and grind 3 corners a touch larger with a dremel.
Wingnut means 3 sides, not corners.
Here is excerpt from another post on how to make one:
Gentleman, i made the mistake of "not ordering online" the odd shaped triangular socket, thinking that i could find it in some local store or i would get one at our local VW guy here in town... Anyway, looked all over import part & tool suppliers with no luck! And our local VW guy has gone out of business!
So, after thinking that i'd have to wait another week for the aforementioned socket i decided to use a little ingenuity and proceeded to fabricate my own out of a 9/32 craftsman 1/4 inch drive 6 point socket!!!
I firmly believe that you should always have the right tool for the job, but since i was in a bind i was able to bore the "triangular shape" into the 9/32 inch socket and since you don't need a lot of torque on that bolt, even though the socket was a little loose, it did the job just fine without ever "hurting" the bolt's head.
Material Needed:
1- 9/32 inch 6 pt 1/4 inch drive socket
Equipment Needed:
1- Dremel type tool
1- Round type "boring bit"
1- Vise grip
Time Required:
About 5 to 10 Minutes.
Procedure: Just bore-out tree of them 6 walls in the socket (leaving one intact in between) in a way to just "round-out" every other wall as to just match the 120 degrees that you'd have within the circumference... and keep trying it in the IP until you get it to fit in!
I had to do this and here are a few things I learned:
A 7 mm socket will work as well.
You only need to take of a very small amount from the 3 sides you grind. When Wingnut says "a touch" he means it. Don't get too aggressive and try to not enlarge any of the corners. Doing either or both of these will result in a sloppy socket fit and a scary time trying to get the bolt to break free. I also has a little play and seeing as this bolt is basically a hex with three factory stripped corners, I was always wondering if the bolt would strip until it broke free (I may have had a particularly sticky bolt).
I too believe in having the right tool for the job but I also believe in saving 23 bucks on a socket I will use one or 2 times ever on a VW tamper-proof bolt that really does not need to be there anyway.
Hope these tips help others.