Well, what you want to be using for pumping oils is a miniature
Quimby Screw Pump. Now I have absolutely no idea on how or where you could buy one, not to mention the high cost of one even if you could buy it, but it'd be one way to ensure decent flow rates.
Quimby Screw Pumps typically form the basis of hydraulic devices. Exceptionally high pressure (up to 2500PSI) coupled with exceptionally high flow (up to 5000gpm for large models - yes - no typo there - gallons per minute), provided you power them appropriately.
I did see a little one about 12in long with a clear polycarbonate shell to you could see the insides. I'd love to have that...