The oil metering pump was a simple mechanical device on Mazda Wankel engines up to ~1991 (the first and second generation rx-7, and I presume other models in Ja

The oil metering pump was a simple mechanical device on Mazda Wankel engines up to ~1991 (the first and second generation rx-7, and I presume other models in Japan.) This was replaced by an electronically controlled pump on all the later models. The advantage of electronic control is that it conserves oil at low RPM. Unfortunately, the reliability of the pump (and the wiring) became a problem. With the RX-8, they had to dial back the oil supply to meet modern emissions regulations and this lead to premature wear to a lot of engines. I believe this contributed heavily to dwindling sales and ultimately to the decision to discontinue the RX-8 in 2012.