CFS3 has always had an oil slick special effect.
(The images above show the lighter, more transparent/iridescent oil textures provided with the all-in-one effects.xml that Daiwiletti and I put together recently)
Perhaps WOTR will have some additional refinements like oil that trails along in the wake of a wounded ship.
To me it looks like the original texture is still being used in WOTR, as it doesn't blend in very well and creates a discrete black/green blotch on the surface.
I love the reflections in the new cockpit by the way...