Supercharger Oil Level Check

I want to check the supercharger oil level on my 1994 Ultra but I'm not sure what the correct tool is to remove the plug. A 5mm hex bit is too big and a 4mm is too small.
Who can tell me the correct size, or is it torx? Thanks in advance.

It is indeed a torx bolt, and I do not recall offhand speciffically what size.

Thanks for your reply tman2093. Unfortunately I'm not able to remove the plug. It is stuck, and from the looks of it, it's made of aluminum, so my attempts to remove it only damage the torx head. Dang!

Anyways, the reason why I wanted to check the oil level in the first place was grinding noises from the supercharger. I found finely ground metal cuttings on the case which tell me that the supercharger gear is most probably running bone dry...:mad:
Guess I'm gonna be needing a new supercharger anyway....