Hi,
Please verschandeln the area at the junction between the engine block and the transmission

, removing all dirt and oil. Then, observe whether it becomes oily again after a few days. If it does, it's likely that the seal is leaking.
If that's the case, you can essentially start from scratch.
Downshift the gears, replace the oil seal, and hope that you can still use the clutch... that's what it was like for me, at least.
I'm not sure if the 1Z also has that "sound-dampening" plastic cover above the oil pan. You should probably remove it before attempting something like that.
In my case, oil had accumulated inside, and during the ride, it probably leaked out from time to time. That's why there was oil in places where there shouldn't have been any.
@
Uwe
Regarding my clutch: It actually only slips in the first two gears.
Otherwise, I am absolutely satisfied with it. I would definitely buy another one, and with a little practice, it works wonderfully.
(Except for these sounds

).
What happens next is a good question. It depends on what else might happen as a result. If things stay like this, I definitely won't be replacing the clutch again anytime soon. However, if there's also a risk to the transmission or something similar, then I would have to reconsider.
Well, if I'm going to do it, then I might as well replace the bearings in the transmission at the same time. You have to think positively, you know }.
See you later.
Thomas.