The bleeding on the back has never a bench mark of telling an original, as lots of repros have some blue on the back edge too. If you know what you're looking for, this sign has a couple red flags. I have this repro posted in the known reproduction section on Old Gas. We don't like to post all the problems here on a public forum due to the fact that the repro scums glean Old Gas and other sites for information on making their fakes better. Anymore, I would avoid any IR54 Mobilfuel offered on Ebay.
FYI, a quick look of completed sales for "Mobilfuel" on Ebay shows 23 results. Of the 23 results, 22 are pump plates. Of the 22 pump plates, 21 are repros!
Always looking for Mobil items I don't already have!