The plug to refill the transaxle is located on the passenger side of the car. Just remove the 4 torx head screws on the rearmost underbody panel and you can see the drain plug and forward and above an identical refill plug.

Phil

 

Just to visualize what Lurchphil said. #1 is the filler plug, #2 is the drain plug. Both need to be torqued to 30 ft-lb.

 

Dealers may not always use Porsche genuine products. I called the service manager where I bought my 2008 997S and asked him what they used when I had them change it before delivery. He didn't know. After changing it to genuine Porsche fluid as strongly recommended by Gbox for the Aisin transaxles, shifting improved dramatically. By the way, the torque for the 24mm drain plugs is 22 ft/lbs I believe. Just don't over tighten! Sunset Porsche has the best prices for genuine Porsche stuff.
About 3 liters is close enough. It won't hurt to be within a 1/4 pint either way. Not like engine seals.

 

I was experiencing intermittent issues shifting into first gear, especially when cold. I just had the dealer change the gearbox oil, bleed the clutch fluid, and adjust the clutch cable. I would say the general shifting is definitely smoother, but the occasional first gear issue remains, albeit perhaps a bit better. The oil the dealer used was Mobilube, and the car is a 2006 C2 with 36K mi.

 

Luxter -- Can you let us know your impressions of the Liqui Moly 75W-90 (I assume you used GL-5)?? I hear it is good stuff, but I am interested to hear from someone who actually used it. Pelican Parts has it for under $18/Liter, so it is good value if it delivers.

BTW, a Porsche tech told me that he wouldn't recommend using synthetic gear oil in the manual transmission and front differential (I have a '06 C4S) since that is not what came in it from the factory. Anyone ever hear that before? Liqui Moly happens to be fully synthetic.

Sean

 

Try Swepco 201