And while you're down there is a good time to bleed the clutch. When I did mine I had some other work to do so I can't remember if I took of the sheetmetal brace and the diagonal reinforcement plates for the transmission oil change or something else, but with those off it is easier to get up to the bleed nipple on the clutch slave cylinder.
I used the Porsche OEM fluid, got it from ECS Tuning which was the best price by a fair margin. Now that Sunset Porsche has an online store (PorschePartsHub) it looks like they have the best price:
ORMD-TRANS OIL 1LTR | Genuine Porsche | 999-917-546-00