Whether you call it the oil flag, the slippery surface flag or whatever, I have always been taught that it is always stationary, never waved. An explanation was given that it can look red if waved.
In a moment of boredom I found myself browsing through the Blue Book and was a little surprised to find Section Q Para 15.1 stating:
(g) Yellow flag with Red Stripes – Stationary: Slippery
surface ahead.
(h) Yellow flag with Red Stripes – Waved: Slippery
surface imminent.
Clearly the BB is the official words of wisdom. Does this mean that my training has been incorrect?