Stripey flags
 

The stripey flags are shown for lack of adhesion in a certain place and are not 'oil' flags... but can be used for oil.

I think the stripey flags on turn 2 were for the wet patches that never dried up. These patches were slippy-slippy (I tested this once or twice).

I didn't see any oil on turn 2... but there was a some cement dust on the inside down the back straight-ish bit (so they had some cementy-stuff at the circuit).