Cruiz, If your model is painted with enamels, beware that oil-based washes may well ruin your paint job! I'd let the model dry for several days and apply the oil-based wash selectively, to particular areas and recesses without dragging the brush. Fill in your brush and place the very tip along a recessed line for instance and let the 'capilary action' do the rest. The wash should flow and flood in the whole recessed line.
If you're not a patient man, use water based artist's colours (watercolours, not acrylics!). They wont ruin any acrylic nor enamel base paint.