FL1, TD4 (M47 2005) Clutch Failed for low oil level.

Hi. The clutch failed on my TD4, discovering there was not enough oil in the small reservoir. Once topped-up it was fine. It didn't need bleeding.
My question is? What is the capacity of this minuscule reservoir and why has it got such a large rubber insert on the lid? Surely this (balloon-looking) rubber insert takes up most of the space in such a small reservoir, which must restrict the amount of oil?
Thanks.

The fluid level is supposed to be checked occasionally, so it should never drop too low.

75ml springs to mind, it's not much.

I believe the balloon shaped thing is designed to act as damper for fluid returning to the reservoir once the pedal is released.

Thanks, Nodge. The level you quote amounts to similar to what I injected. Yes, I used a small syringe, 20mm x3.