yeah,  most  have that  system..  adjustability?   not that I'm aware.  
I do know that  if the  spreader brush is  worn out/missing,   it makes more of a mess.
you want more oil? - just  cycle the door a few times every  10-15 bales.  
how heavy the windrows are,  and  how often the door opens per hour  really changes how much oil is being squirted out.

NH  did have a system  on their early chain balers that  when the tailgate was open,  the reservoir (on the tailgate)  would tilt and fill a small chamber,  then when the gate closed,  that small amount ran out via gravity to the chains.