Restoration Paint (?) or Plating ?

[David_VG30DETT]

Some of you may know I own a Commemorative '96 Z-32 s/n 258 / 300 which is assembly-line stock close to a '10' as you'll ever find and just turned 11K
original miles.

I had a problem over the past Summer where an electric vent damper in my climate controlled garage malfunctioned during an extended absence and the resulting high humidity caused some surface corrosion under the hood to a few bolt on engine components.

Nothing too serious but I want to keep this Z as Primo as the day it was built.

Well long story short, the affected metal (Cadmium) plated items were replaced with OEM NOS which took awhile to find.

When I received the Power Steering Fluid Reservoir it came as a "bare metal" OEM replacement part from Nissan.

The original PSR has a Deep Olive Green surface coating --- (Paint or some type of Plating). There are a few other items under the hood which have similar surface coatings like the Cruise Control Electric Actuator.

Does anyone know what this type of Surface Coating might be on the Power Steering Fluid Reservoir ?