When you put multiple types of materials together and push oil through them, eventually it will start to leak.
The Mazda rotary engine is a combination of aluminum, steel, cast iron and gasket materials.
Add in heat cycles and horsepower and these expand & contract many, many times. Eventually, oil will find its way out.
From our experience, the most common are going to be the oil pan, coolers, lines and the dreaded rear main seal.
One thing that most people are not fully aware of is that oil performance is based on volume / flow. This is why as performance increases, the demands on the oil pump and every sealing surface is critical for reliability.
While the rotary engine design is a bit different, the maintenance is the same, keep oil restrictions to a minimum and pay attention to small leaks. It is a lot less money to repair a small leak vs. wait until it becomes a larger issue.
This also allows us to repair any wiring on the gearbox (we see these wires up close, they usually need some attention). Fresh and clean on the outside means it will run cooler along with fresh fluid inside for longer life.
The bottom line is that having a cooling system that is free from oil / debris (inside & out) is always going to increase performance and life of the engine.