An easy way to enhance the look of any diesel locomotive is to blacken the grills and vents to provide more depth.  You can use a black wash to bring out the grill or vent details.  Weathering powders are extremely effective bringing out locomotive vent and grill details.

Micro-Trains Line Logging Camp Cars #3 Build

I built the Micro-Trains Line Dormitory Camp Cars Kit #2, now I am going to document the build [ ... ]

Hopper Weathering Clinic
By Bill Mock
December 2009

Here is the first stages of weathering of my new BN [ ... ]

 This is Micro trains Line SD40-2 Santa Fe model which I customized with working ditch lights.