Why does the Aroma Reed Diffuser oil colour turn slightly yellow few days after I use it? And why are there sometimes some solid particles in the oil?

Heat the rest of the oil in a casserole dish and fry off the Onions, carrot and rosemary until just softened (with no colour).

This paper explains the image expansion and confusion of the red and blue primary colours caused by the electric charge accumulation on the oil film in the colour TV light valve tube.