I do oil pin washes over acrylic clear gloss coat so the wash can run freely into the recessed details. For filters, DOT weathering, streaks etc I like to use oils over an acrylic flat coat because I find the flat finish makes the oils blend better than over gloss which in my experience seem to come right off, making blending a bit difficult.
During the last model show I attended, they had a weathering seminar where the instructor used DOT oils over a Tamiya X35 acrylic semi gloss to weather individual NMF aircraft panels. He expained the X35 gave enough tooth for the oil paints to bite but made it easier to manipulate than over clear flat. I really liked how the effect looked over the sealed Alclad.