Diesel engine too clean.

Nice filthy diesels. All the dirt and oil is watered down Testors black gun applied with cotton swab and wiped with paper towel.

Before oil/grime and decals.

After: nice and grimey. There are like half a dozen tiny decals that will go on this bulkhead alone! Much of the grunge will be covered up.

Black paint thinned down and rubbed to add definition and grime.