Oil stain under the car - transmission fluid or brake fluid? (Solution)

Hello fellow enthusiasts,

My usually reliable vehicle (see below) is currently experiencing a minor 'incontinence' issue.

I discovered a small, yellowish, oily stain in the garage.
First, I thought it might be brake fluid (rubbing it between my fingers, it lacks that oily feel), but after inspecting the underside, I didn't find any traces on the underbody panel .

It was only on the lift that I saw a yellowish drip hanging from the transmission bell housing, directly above the middle mounting bolt of the front underbody panel (at the ventilation opening) ! There were no visible signs on the outside, so it definitely originates from inside the transmission housing.

Now, the question (before I bring out the big guns):

1.) Could it be brake fluid leaking from the clutch slave cylinder (I'm not familiar with the internal design of the clutch actuation system on the transmission)?
2.) Defective oil seal --> but is it transmission oil? I have never heard of damaged shaft seals in these gearboxes (DHF) before.

I look forward to your replies.

Best regards, Oldi.

If the liquid dissolves in water, it's likely brake fluid; otherwise, it's most likely transmission oil.

Hello Autoservice,

Thank you for the tip .

I will examine the new stain immediately (now I've cleaned everything up nicely).
However, I had the feeling that the liquid washed off very easily with water from my fingers, so I'm hoping it's brake fluid...

Does the receiver cylinder leak more often?

Best regards, Oldi.

Hello fellow enthusiasts,

It was (fortunately) actually brake fluid that was leaking from the transmission bell housing !

With the mention of the water solubility of brake fluid (yet another thank you to 'autoservice' for the incredibly quick tip), it quickly became clear what was lurking on the garage floor...
After I saw the exploded diagram of the gearbox with the clutch slave cylinder installed, it was clear that the leak must be coming from that hydraulic component.

BTW: It's hard to believe, but the clutch feels noticeably smoother, even though the cylinders are identical (both are VW-AUDI parts, 8D0 721 257, manufactured by Sachs).

Best regards, Oldi.

Luckily, it was only the cylinder, and thank you for the feedback .