Artistic oils are most excellent for painting plastic as wood. I've done laminated wood with them (WWI planes), old wood and oiled wood (sailing ships), red wood and bark (decorations and diaramas) of any shade existing and plenty non-existing. Most excellent; I'm a loosy painter, but I was awfully impressed with my results. I will not exchange my oils for anything in the world. :)
The price of the very best quality tube of artistic oils here is under $10, I've bought 6 tubes, and that gives me any shade of wood I can think about plus white and black for washes and shades. water-soluble "oils" simply doesn't work this way. There is two ways for me to thin oils - with pinen and with some seed oil - first one make oils "rougher" a bit and cures in 3-4 days, second one makes them very soft, but after that they cure for weeks.