I would be calling Deman, Sharkwerks or guard transmission and asking

 

Incidentally the installer and supplier of the differential said to use the Motul Gear 300 LS whereas the actual manufacturer of the differential said to use the Porsche OEM fluid which is the Motul Gear 300.

Ask 1000 people and about half will say one, and half will say the other.

And so OEM-equivalent Gear 300 it shall be.

 

Not an expert, but as best I can tell the stock oil is without friction modifier, for open diff or stock LSD. The stock LSD is very low lockup though, if you're moving to a stronger aftermarket LSD it may very well want friction modifier. Really the LSD manufacturer is who you should be asking. Once you make a substantial change from stock, stock specifications don't really apply.

 

OEM oil does have a small bit of additive from the factory.

The upgraded differential is essentially the same setup and form factor as stock except it’s made of superior materials and will put the power down better due to enhanced gearing.

The differential builder went through all the particulars and he said the LS variant/additive would make things too slippery and would dramatically raise operating temperature. Maybe counter-intuitive but he knew what he was talking about. Even aggressive street use doesn’t justify use of the LS additive. OEM all the way, he said.

 

So you have your answer then.