Messieurs !
How to emulate liquid/mud splashes or oil splashes on a model?
Dilute the paint you opted for well, take a brush and dip it in.
Then take a toothpick or what comes handy and bend the hairs of the brush back.
Now aim well at the area the splashes shall go.
Release the hairs - and voila, splashes are there!
Now you will have to hide from the topkick of your squadron....
Nice thing about it: splashes will look like gone with the airflow
This method also works well with wheathering jeeps, lorries and tanks or boots etc.
You may test it first on a sheet of paper
Horrido! Gunther