6 Colors for Double Primary Palette

These are the six colors that I've been using from Holbein; Duo Aqua Oil Paint. There is a warm and cool version of each of the primaries. They clean up with water. No smell. Easy on the environment! I don't like to thin them out, so I haven't done any research on which thinner to use. If I did, I'd see what Holbein has or recommends. I know there are products by Grumbacher and Winsor Newton.
I still use gessoed boards just as I did for traditional oils. I've been using Kamar spray varnish that I used on the oils.
Been working all this out for new book, so any suggestions would be appreciated!