Positive Crankcase Ventalation. Its the hose coming out the drivers side of the valve cover and runs back to the intake. When the PCV goes bad, there is tons of blow-by and it covers everything: intake=> turbo => charge piping => ic(s) => tb. It goes in this loop and will kill both performance and oil supply. You best bet is to a) change the pcv and clean everything or b) add in a catch can and clean everything. Regurdless everything needs cleaned and the oil needs to be stopped.

 

You probably won't see oil on the garage floor, unless theres a massive oil leak, theres a large plastic belly pan that fits under the engine. If anything was dripping, it'd land there.

I'd also like to add, if you checked the oil, and its visible anywhere within the \____/, you're still within normal operating range, (not saying that you shouldn't try to keep it on the higher end)and that shouldn't be a reason for the oil light to come on.

W/o my manual handy, I can't recall if that light comes on when oil pressure is low, but I'd assume it would. My first course of action would be to change the oil (and it kinda looks like its time anyway judging by the color in your pic), and make sure you're using a quality full synthetic oil. I use Mobil 1 5W30. If you're still getting the oil light, then it might be smart to consider taking it to a garage.

 

The light does come on usually followed by the car shutting off. But thats what i have seen in the A4 forums with sludge problems.

 

my oil light came on when my oil level dropped to the minimum mark on the oil dipstick. After adding oil back to close to the Max mark, the oil light goes away.