Oil Pressure sender leaks

The thing I see is that you are running full synthetic oil. In my experience, full synthetic oil will show you where the oil is going to leak everytime. We ran 10w40 full synthetic oil as an experiment on a newly machined and built engine. It had more leaks than a pasta strainer, we took it back down, cleaned and flushed the engine and ran a conventional 10w40 oil and it didn't leak a drop.