I'd always been taught that you couldn't paint over oils with acrylics because of adhesion problems and drying problems leading to cracking. Recently while looking around the net I came across a Gnome DVD with Dave Dorman showing how he paints. Apparently, he paints acrylics over dry oils.
Are there any rules to this and will he run into problems later on? I plan to buy his DVD just because I'm so intrigued with how much he mixes his media. In the free video you can watch he even uses markers over the oils. I plan to try all this but thought some here may have tried before.