Instead of Turps use Shellsol T : a turpentine substitute derived from petroleum - manufactured rather than distilled and therefore it is purer than turps.

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Mix  Shellsol with linseed or walnut oil to create a generous flow medium  - 
depending upon how 'washy' you want the medium -  you will need to experiment with the quantities before embarking on painting. I would also check for drying times, and if too wet - experiment with adding some liquin to the mix.