I had a factory drawing that shows a 6mm hex head on the full screw. After pulling off the plastic air inlet I can see the head is smaller than 6mm. Cannot get a 5mm started either.
From the people here that have changed the oil on a X350, what is the correct hex head for this port?

 

3/16 Allen key put some rag under the plug it's a fiddly job and easy to drop the plug

 

I crammed two blue shop rags to make a saddle to catch the screw when dropped. And a magnetic rod for pickup.
We expect 8 - 10 inches of rain tonight. May get the fluid changed tomorrow.

 

Took 45 minutes to pull the cover, the air inlet, and the screw. The screw must have had debris it took a bit to get started. Vacuumed out 6 oz, and refilled till a hose volume drained out. Took 90 minutes total to button back together.
This may have been performed by the previous owner. The fluid was honey colored. Definitely cleaner than used motor oil, which is black in the vacuum hose. This was dark brown.
May do again in 25 - 30k miles. The 2 oz left in the supercharger may have had all the metal bits.
Got dark before I could change the fuel filter and tighten the screws on the shifter cable bracket. Maybe tomorrow.