What Allen Wrench size does the truss rod of a MiM Fender Standard Telecaster use? Their official site doesn't specify it.

I had lots of Allen Wrenches but they were too small, a friend borrowed me a 3/16 (5mm) Allen Wrench and it fitted but I couldn't turn the tross rod on any side, it was simply too hard, and I'm not sure if it could actually go down all the way down of the hole.

I'm thinking in buying a 1/8 (3mm) Allen Wrench, I've heard this works with most truss rods, am I correct? My Truss Rod holes looks weird, it has 6 pieces that form a star pattern. I actually tried fitting a screwdriver but it didn't work.
Actually I got the correct key, I just had to loosen and move the strings away from the whole.

If I had fret buzz in the first 12 frets should and my action is too low at the nut should I tighten or loosen the truss rod? Should I move it counterclockwise or clockwise? I've tried moving it on both sizes but I got lost and actually managed to increase the fret buzz ;_;