You might find interesting to discover that oil is widely used not only in gasoline production, but in heavy-tonnage versatile organic synthesis as well. Almost all mundane things around us are currently produced with some use of oil and gas, thence the tendency towards global hydraulic despotism. See, alternative energy sources can’t reliably cover this base. So Petroleum Age is far from end, it’s possible that sometimes hydrocarbons will be economically feasible to mine on, say, Titan.