Thank you, gentlemen.
Wash is not oil. I prefer something very easily correctible - I am using simple water paints which, when finally washed are sealed with a clear acrylic coat.
As for the Citadel paints I am lucky to own still some from their old line, which were not so dense as the newly released. Unfortunately the new ones are completely useless for airbrushing, hard to dilute and the metallic ones have very coarse pigment blocking the nozzle. The old ones were much finer and require only moderate diluting for airbrushing.