There are lots of cheap plactic manual oil pumps that can screw onto a one quart or one liter oil bottle. You might like to look for one that includes the little metal adapter fitting that will screw into the Zerk fitting threaded port. Also one with longer stroke pump for more volume with each push.



I rather like this one, adaptable to short quart oil bottle, tall quart gear lube bottle, one gallon jug, and with a long stroke pump. It might require two hands to hold the bottle and work the pump as your third hand holds the spigot in the fill port.