Yes I have and can do a wonderful job in weathering particularly for producing areas of exhaust stains, grime, rust stains and also is good at making tires look dirty. The product is essentially a pastel mixed in a oil like base.  I have found it has to be used in the final step as clear varnishes seem to wash the product and your hard work away. I found it helpful to buy new applicator pads and brushes which are cheap, thereby not contaminating one color with other colors.

The kit will last you a very long time.

Hope that helps

Doc Sudy