The folks at Vasari put together this video showing what happens to cadmium yellow lemon (opaque) and Indian yellow (transparent) when you mix them with reds and whites. The factor of transparency greatly affects the value and chroma of the mixtures (Link to YouTube).
If you want to make such tests yourself, you can use a palette knife on glass with a black backing, or you can mix them in the form of a chart in a canvas paper pad.
Vasari oil colors
Color and Light: A Guide for the Realist Painter