Hi Chris. I also used artist oils and acrylic ink for my pin washes but recently have moved over to nornal water colours, the tipe they sell for the kids- those little blocks in a molded plastic case.
It is very cheap, you can mix almost any colour and it is also easy to remove the eccess ut like any wash it needs to go over a very gloss base, I use tamiya clear acrylic as my gloss.
I also dip the tip of my paintbrush in some dish wash soap when I start mixing the wash as it "thins" the paint and water and lets it flow better.
Give it a go, it reallt makes detail "pop"
Theuns