No it started doing it about a week into the oil change and intermittently. I've driven the car while it was doing it, we figured it was the sensor going bad since it was so random when it would do it, sometimes it would go a few days without doing it. It also sometimes would do it before the engine and oil was even up to temperature, sometimes only after hot, sometimes not at all. The oil smelled fine both times I changed it and the level never changed either. The engine has 177,000 miles on it. Even when the low oil pressure warning came on, I could see a good amount of oil flow through the oil filler cap. We will see what happens.
I do find it extremely odd how much smoother and quieter the engine sounds after putting the OEM filter and 5W30 in it. It does not even sound like the same engine at all and it sounded pretty good before.
Sounds like the the symptoms were way too random to be caused by the oil filter, especially if it it comes and goes days apart. If it was the filter, it would have started on day one and stay constant, not a week into the oil change and come and go intermittently. I say that because if it started a week after the oil change and wasn't intermittent, and you saw something not right with the filter after you cut it open, then one could say it was a failure of the filter verified with a cut-open and a discovery of something off base. But it looks good with zero signs of a failure.
And it couldn't be the filter's bypass valve, because as I mentioned earlier the oil flow volume and dP across an oil filter at idle is low. Idle pump flow rate is probably no more than 2 GPM, and at that flow rate with hot oil the dP across the filter is real low, like less than 3 PSI. There is no way the oil pump could even get close to hitting pressure relief under those conditions.
How do you know it's not an intermittent in the oil pressure sensor circuit? Doesn't necessarily have to be the sensor itself. Did you run any diagnostics to look for trouble-codes?
My guess is with that many miles on the engine, there is something starting to happen with the oil pump. Do you know if this engine has a variable volume oil pump on it? If so, could be the control system is whacking out intermittently. As
@twX said above, a proper oil pressure test with a mechanical pressure gauge connected to the main oil gallery would tell you if the oil pressure sensor system was right or wrong. But again, if it's an intermittent thing going on, then it makes it another level of difficulty tracking it down.
