As usual, Taylor is right on the money as far as I know about most of this stuff but there is one thing I would question. The one and only tank car that the S.V.R. had was indeed all silver and for some time I to thought it was painted black in the center. But after looking closer at these pictures I believe that a large amount oil had been spilled and around the loading hatch and covered the center of the car in an oil black color.
In the end, I believe the tank cars was ALL silver with a messy dried oily mess in the middle.