My experience is in 12a's. As I understood it, the nozzle was directly under the jet for the fuel and this mixed the oil and gas during the atomization process and created lubrication magic. I now have a 13B from an GSL-SE and looking at the engine. While the 12a only had two lines coming off of the OMP, the 13B has 4 lines. Two lines go directly to the rotor housings. That make sense to me. What I am having issues with are the ones in the lower intake manifold. They are in the primary runners and seem to be metering oil into the middle of the runners. Is the idea here that the velocity of the air flowing through the runners will atomize the oil? I was expecting to see it closer to the fuel, like my old 12a's did.

 

so basically the idea is to get more oil to the surfaces that actually need lubrication, and less oil into the combustion chamber/atmosphere.

Mazda did a study of metering oil flow in the Rx8 engine, and found that even though it uses only the metering nozzles on the rotor housings, there is still a big percentage of oil that doesn't get to where its needed.

the GSL-SE is an intermediate step, as its offering oil up in two places, the FD just has the one on the rotor housing.