A member on another group responded to a request for info I posted on any site, regarding these. He posted photos of other identical ones (exact same diameter and hole placement) from
Sohio Texaco, Standard, and Ashland. All had the same era logos from early 60’s. His account of how and when he obtained his is not in dispute. I have no reason to believe that these, like his are reproduction. These are not porcelain. They are quite thin. No good reason to reproduce something like this. They are small, have a relatively modern and boring logo, and serve no purpose to be reproduced. If they are reproduction, then I would expect to find at least one other example of these. I would not rule out them being “aftermarket” as someone else mentioned. That is, they could have been made by some company for the gas industry and sold them for various brands during the era of those logos. For what purpose is yet to be seen. I agree that I personally don’t think they are tanker door plates as someone had suggested. I can Google plenty of pics of tanker trucks and nothing close to this, plus it would seem like anything on a tanker from that era would have a decal or something, but not a little screw on plate.