We just had a sensor failure on the oil pressure feeding the MV50 and Chelton in a friend's Legacy.    The pressure was not zero (3-10psi) and the mechanical gauges confirmed engine oil pressure was normal.   Sensor replaced, all is well.   7 QTs is normal in my Legacy.  5 or 6 quarts is definitely an add level for me.  Good luck.

Paul
Spruce Creek