I heard someone mention a while back about smoke colours.... im pretty sure one guy used diesel fuel oil mixed with a small amount of food dye.. you can buy it in the supermarket. The best smoke fluid i have seen used for white though' is diesel and transmission fluid mixed 50/50, gives a really deep white/grey smoke. Also instead of the food dye, I beleive you can use ink from pens, like a biro, just cut the tube and get the ink out, a few drops in the oil should soon change its colour. I have never seen it used myself but might be worth a try ?