Very nicely done Roland. I am partial to models that attempt to show the effects of what I sometimes call "WAD" (wear, abuse, damage) and yours is another fine example. I am appreciating, and using, more and more oils to achieve better effects in this area. I learned what is sometimes called the "dot filter" effect when building armor models. I use four or five different colors of oil paints applied in very small dots with a toothpick in random spots over the surface I will be working with. I use sometimes odd colors such as blue, red, white, yellow, black, etc. that don't have counterparts in the basic paint color scheme. Somehow these usually combine to create realistic tonal and color effects anyway.
I will then use a wide, chisel shaped brush with short bristles, dampened (slightly) with turpenoid or other oil thinner, and blend the colors, brushing in a logical direction, such as along the airflow lines on wings and vertically along fuselage components, etc. until I get a varied, multi-hued effect that looks good to me. I'm sure there is some artistic, color basis for this, but I don't know what that might be. I like to visualize where the light might be coming from on a subject and go for lighter and darker areas accordingly.
I think oils have a wide application in modeling, especially in weather beaten, abused and ageing WWI aircraft.