I have a 1999 986 automatic Tiptronic and I began having a noise from my differential. So, I jacked it up on my Quickjack and I was able to get the differential hex nut off,

and I noticed the fluid is very low. I can get the complete tip of my finger down inside the whole and still can't touch any fluid. Is that normal or shouldn't the fluid atleast flow up to the hole? I have the fluid already, but I didn't wanna add any until I know for sure. Any feedback is greatly appreciated. Thanks!!