Re: The stones were green when I used olive oil and yellow when I used rapeseed oil...

To confuse you a bit more - I have flushed mostly with olive oil, but also with sunflower oil and canola oil, and the colour of stones I get does not change with it. I usually get several different shades of green stones on the same flush, plus tan ones ocassionally. (Still remembering fondly those beautiful jade green pebbles from my third flush ... how weird is that?) When I added curcuma to oil/juice mix, it seemed to colour chaff yellowish, but not stones. Did you try to cut one open?
Anyway, I just wanted to assure you that what you saw was totally normal. Flush on with canola if you want or return to olive, it will still clean up your liver and gallbladder either way.