PTX is a Mobil product. Porsche's current marketing/ lube supplier is Mobil. They get stuff for free or nearly free for the cars rolling off the assembly line in exchange for putting a sticker on the engine lid. Includes oil, gear oil and gasoline. German manufacturers do this. Sometimes it is Castrol and Shell. The free advertising carries a lot of influence with unknowing consumer world. The choice of a major oil company is also based on worldwide recognition and supply for the aftermarket. The cars are sold everywhere in the world so materials need to be available. The good news for us is that the PTX product is excellent in our Japanese transmissions. Just use it. As to motor oils, the sticker on your engine lid says "Mobil !". However Porsche has an approved list of many oils that they have tested and determined are adequate for use in their engines. The products are good but the marketing is tremendous.

 

Thank you for the replies! The reason I asked is because I can easily get the factory fluid locally. I drained and refilled using the factory fluid ~30k miles ago and it has been fine. I think that I’ll go with the factory fluid again if it’s the same thing and will probably flush it out at the next oil change.

 

The reason for the upper hole: Just a guess, but perhaps to fill the transaxle with the correct level plug (lower) removed, allowing for more accurate measurement of fill. I believe Porsche recommends approx. 1/2 an inch below the fill plug, although most folks (including me) fill until they see it just starting to come out of the correct (lower) level plug hole. Or maybe even to vent the transaxle if they have a special fitting that screws into the lower fill hole and completely seals that hole as they fill with a pump. As I said, just a guess on my part.