Looks to be unique among the collectors here...
It would make sense if the farm was far from a railroad station/town. And if it was a big farm, big enough to have motorized equipment and trucks.
I imagine this Holt Gasoline Caterpillar Tractor went through a lot of oil...
http://en.wikipedia.org/wiki/File:Holt_Gasoline_Caterpillar_tractor_1914.jpg
as did these Avery tractors:
http://en.wikipedia.org/wiki/Avery_CompanyThere was also the Model T Truck and the 1914 Avery 3 ton Country and Farm Truck and other brands of tractors and trucks used at the time of your oil dispensor.
I wonder if that same farm also had an underground gas tank? Would have made sense...