This will give you the look of accumulated dry grime on an engine or underside of a car, brake drums, etc.
This enamel based paint just needs to be painted on.
Apply with a brush in different layers of different intensities for the most realistic effects.
Instructions are not included but I have a free downloadable PDF file combining a few AK Interactive 'How-to use Product Guides' (specific to this weathering set).
One 35 ml-bottle, by AK Interactive.