If it was me, I would be fitting a genuine Nissan EOPS as they are only circa £40.00.
Do you not have a mate with a similar car that you could swop out his sensor as a process of elimination?
If you are sure that the new sensor is good, then I would be looking at associated wiring or a bad connection.
The engine oil temperature sensor is used to detect the engine oil temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the engine oil temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.
Plenty preowned heads to choose from in this for sale thread: https://www.350z-uk.com/topic/125665-loadsa-parts-for-sale-picture-heavy-now-with-prices-and-detail/
I can't advise on what to buy until you answer my question.
This might help you understand my question: https://www.webuyanycar.com/guides/car-ownership/types-of-speed-cameras/