Hmm. The PDK wasn't available until 2008. Assuming that you meant 2008/PDK, then there are two types of fluid that are used in the PDK gearbox:
PDK transmission oil - approx. 3.12 quarts ATF transmission oil Mobilube PTX Formula A (SAE 75W-90) GL 4.5 - change at 120K miles or 12 years
PDK clutch oil - approx. 5.49 quarts Pentosin Gear Oil FFL 3 - change at 60 K miles or 6 years
Looks like you need the PIWIS to perform the check after refill.
Oil filling
• The correct hydraulic oil level is important for operating the transmission without running into problems. The following preconditions must be met in order to check or correct the oil level:
• Engine must be idling
• Vehicle must be horizontal in both longitudinal and transverse axis
• Hydraulic oil temperature between 86° F. and 104° F. (30° C and 40° C)
• Selector-lever position “P”
• Clutch cooling volume flow must be switched off (using PIWIS Tester in Oil fill mode)
• Retain the described states for approx. 1 minute to allow the oil to settle
• Open screw plug on oil overflow bore and collect emerging oil until only drops of oil are emerging
• Once there is no more oil emerging, top up the clutch fluid until oil emerges at the oil overflow bore
• To avoid damaging the clutches, the procedure must be completed within 5 minutes (PIWIS Tester exits Oil fill mode automatically after 5 minutes)
This is a good link:
PDK / Gear oil - 997-2 Series (Carrera, Carrera 4, Carrera 2S, Carrera 4S, Carrera GTS, 911 Speedster) - RennTech.org Forums