Pump Lift is the linear vertical measurement that indicates the distance a certain pump can draw a liquid from the intake to the pump body and the moving parts which will compress the liquid and eject it through the outlet side of the pump.
The physical properties of materials like viscosity and density can impact the lift performance. Because oil is less dense than water the lift will be greater because of the ratio of weight to volume. Less weight is being lifted by the vacuum the pump creates in the inlet so a less dense material can travel higher with less energy than a denser liquid like water.
The reason a pump cannot deliver fluid to the pump body and the moving parts that will compress it and force it through the outlet has to do with the interaction of different liquids with the partial vacuum that the pump is creating in the inlet.
In an experimental display we would be able to see containers of liquid of various densities each container would include a clear vertical tube which has had all matter pumped out (actually impossible) to create a perfect vacuum. We would see liquids drawn up to a certain height by a combination of the pull of the vacuum and the push of atmospheric pressure on the liquid in the container.
Since no pump produces a perfect vacuum in the inlet the maximum pump lift of the same liquids in a real world situation would be reduced because of the inherent inefficiency of the pump mechanism.