AMMO by MIG EFFECTS BRUSHER - Fuel Stains

From the Manufacturer:

Featuring a long-haired precision brush within the cap, you can apply mechanical fluid effects that give your models a personality and extreme realism. Fuel, grease, and moisture spills are now much faster, cleaner, and easier to apply. The enamel-based formulation provides the ideal working time. This product should be thinned and cleaned using Enamel Odourless Thinner A.MIG-2018.