Sealing elements for rotating shafts: in general, PTFE is the plastic material that has the best friction characteristics. It is also called Teflon.
It has the consistency of a kind of butter, for which it is loaded with bronze or other materials such as graphite, depending on the material with which it is to be coupled. PU, polyurethane, is similar to an elastomer, so no bronze is needed.
These gaskets are loaded in 2 ways:

In general it is the shape of the gasket that makes the application (roto-translating or only translating). In our case, given the shape of the throat, we can not get any better.
We chose the PU instead of the PTFR because it behaves better at p ↙, speed ↙, driving games ↙.

MQL is a lubrication system through which an oil-air aerosol is created at the tool work point. It allows to use the minimum quantity of oil in the current state of the technology.

I remember that a pressure drop in a nozzle corresponds to a drop in T (and the consequent creation of aerosol, or fog):
Mollier diagram