I would think that with all the Gargoyle items in that photo it would be early 30's at the latest, probably earlier. Before the Socony Vacuum merger, Vacuum's Gargoyle Mobiloil was sold everywhere, at almost any brand gasoline service station that wanted to sell it, including many small independents that were in the gas business, not motor oil. Gargoyle as the major trademark was pretty much phased out by S-V by the late 1930's, with Pegasus' introduction in the early 30's.
After the merger, Mobiloil became more of a sole property brand and was sold through Mobilgas retailers or S-V jobbers. Also by that time all the other companies were trying to build brand loyalty by selling their own motor oils, say Gulf or Texaco, in branded cans.