I have a 2000 expedition with a 5.4 it has started giving a low oil pressure light when cold gauge goes to zero also.This just started it will do it when you start it for the first time of the day it comes up for a few seconds, then goes to zero and will go up when you start to drive and maybe do it 2 or 3 more times and not do it again. Oil level is fine. Going to try new sending unit.I'm hoping this is just a sensor problem and not actual oil pressure. Thanks